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1. To update a version copy the latest tarball into the directory and run the install script of the new version It will automatically shut down the old proxy and run the new one This takes less than a second and all registered users will be still registered Even ongoing phone call will continue as the proxy keeps only little state information about ongoing calls however ongoing calls will not go to the call log Typically users will not observe the updating process 26 e Installation General Concepts Some general concepts need to be explained before you set up the proxy Security When a request arrives at the proxy it may trigger actions requiring security measures Examples include e dialling numbers that cost money e avoiding anonymous calls and e avoiding attacks like hanging up calls without being involved The principle for authenticating requests in SIP resembles the mechanism used for http called challenging It can be illustrated like this e The user agent wants something from the proxy and sends a request to the proxy e The proxy says thank you but in order to do this please answer the following question The proxy keeps a list of questions that are open and discards them after a timeout e The user agent checks if it can answer the question If it can it sends a new request that contains the question if it can not it gives up e The proxy checks if the answer is correct and corresponds
2. Error Information Generic Destination sip error snom de err fcode Code Destination 403 Forbidden sipipayment i92 168 0 22 400 Bad Request wi You can simply set up the error information redirection by selecting the approriate error type and enter the destination that should be put into the response If you dont define a destination for a specific error code the proxy will take the generic destination This generic destination may include the pattern code which will be replaced with the error code e g 404 If your media server unerstands additional parameters in the number then you can set up one error explanation account for all codes If you leave the generic destination empty and no specific code has been set up no error information will be generated The following error codes are available 400 Bad Request This is a generic error which is not explained in detail 401 Unauthorized The request needs authentication usually the user agent will try again automatically If they don t have the right credentials it can inform the user that they need these credentials 402 Payment Required The call requires payment 403 Forbidden The call is forbidden this may be because the proxy s dial plan says so or because other network elements think so 404 Not Found The destination cannot be found 405 Method Not Allowed The destination was found but does not support the request type 406 Not Acc
3. SIP proxy Microsoft Internet Explorer Datei Bearbeiten Ansicht Favoriten Extras 7 Zur ck 2 EN a A pa Suchen Se Favoriten GA Medien 4 A 3S Links 8 Kttp 127 0 0 1 5068 v Wechseln z snom VoIP phones u Main of Administration Status Adresse english SS a gt Administration Status 7 i D k ei a D e e L 5 kel e WW Dee A j I e OI nr Internet 24 e Installation snom 4S Proxy REGISTRAR MANUAL directory will have subdirectories for the different proxy versions and for registrations It typically also contains the configuration information ed usr local mkdir snom proxy cd usr local snom proxy Extract the files from the tarball ou 7 ed usr local tar xvrz Snom Sip proxy 1386 linux 2 14 tgGz If you are updating a version you may stop the proxy with rcsip proxy stop and remove the symbolic link pointing to the old installation This will force a completely new installation After this you can continue the installation in the directory where you extracted the new version cd snom sip proxy 1326 linux 2Z 14 The tarball includes a shell script with the name install sh which sets up the neccessary files and links for you install sh The file etc rc config for SuSu Linux and etc init d functions for RedHat are appended with the variable START_SIP_PROXY and the SIP_PROXY_OPTS variable is set t
4. H H 323 7 HTTP 7 42 I Installation 19 Installation Directory 20 Instant Messaging 11 Interoperability 3 8 16 IPchains 16 ISDN 7 snom technology AG e 69 snom 4S Proxy REGISTRAR MANUAL J Jitter 11 L LDAP 11 Logging 65 Log Level 41 Loose Routing 32 42 58 M Mailbox 9 13 17 Maintenance 59 Max Forwards 39 Media Server 3 13 17 Messenger 8 11 Messenger Registration 56 Music on hold 13 17 Name 59 NAT Gateway 13 41 Network Address Translation 15 16 31 North American Dial Plan 48 O Open Standards 8 Overlap Dialling 30 47 P Packet Loss 11 Path registration 15 16 Ports 21 PPPoE 16 Private IP Address 31 Private Networks 16 Probability 9 30 59 Proxies 12 70 e Index Proxy realm 36 PSTN 9 13 PSTN Gateway 41 Public IP Address 31 Public Networks 16 Q Quality 9 R Realm 28 Rebooting 23 Record Route 42 Redirect 11 Registered Users 59 Registering 55 Registrar 12 59 Registration Time 39 Release Notes 67 Reliabilty 28 Replace International Prefix 41 Route 42 Routing 32 RTP Port Range 16 S Save Registrations to File 39 SDP 16 Security 27 Sequential Forking 15 30 42 Setup DNS 53 Signalling Gateway 13 SIP 7 SIP Message Flow 63 SIP NAT Gateway 16 SNMP 11 snom 100 Registration 55 Soft Switch 3 State 29 Stateful Forking 15 snom 4S Proxy REGISTRAR MANUAL Stateless Proxy 16 Supplementary Services 8 Switched Network
5. e Duration The duration of the call in hours minutes and seconds e From The originator of the call If you click on the originator you see all SIP packets that were involved in this call e To The call s destination Call Log Date Time Dur From To Oct 7 16 56 06 00 00 55 sb snomag de rmasnomag de ier fy abate eG 00 00 07 am snomag de sm amp snomag de Oct 7 15 47 29 00 00 03 sm snomag de am snomag de Oct 7 15 47 00 00 00 11 am snomag de smim snomag de Oct 15 46 06 00 00 35 am snomag de smiasnamag de Cees Leon 00 00 27 am snomag de sm amp snomag de Oct 7 15 34 04 00 10 53 sm snomag de am snomag de Ee 00 00 57 sm snomag de am snoamag de Oct 15 24 06 00 06 34 101 intern snom de jpa snomag de Oct 7 15 27 42 00 00 18 abh snomag de rmasnomag de The call log stores only the last 100 calls and discards older calls The call log is only reliable in so far as the involved network elements follow the loose routing of the proxy If network elements violate this rule snom technology AG e 61 snom 4S Proxy REGISTRAR MANUAL the packets do not flow through the proxy and the proxy is not able to determine the length of the call Please remember that the call log is sensitive information and Should not be accessible to unauthorized persons See the comments on security in this manual Pending Calls Similar to the finished calls the proxy keeps a list about the not finished calls Because in SIP a failure
6. File S P ont off Min Registry Time fsi 600 Max Registry Time si 3600 Default 9 0 000 1 000 Aue Reject Registrations e e Across NAT an att Save Require Authorization If the flag is set to on all registration requests for the proxy are challenged for authentication This means that unknown users can not register on the proxy If the flag is set to off only Known users are challenged that means the proxy is open for registration The list of users is discussed below Trace REGISTER Tracing REGISTER messages in the proxy trace is sometimes undesirable because it just fills up the trace If you turn this flag to off 38 e Configuration snom 4S Proxy REGISTRAR MANUAL REGISTER messages and their associated replies are only traced in the Registered Users window behind the link see below Save Registrations to File If you turn this flag on the registrations are stored in the registrations directory see crash recovery above The directory name is set up during installation Min and Max registration time User agents register for a specific amount of time If a user agent does not refresh a registration before this time the registration is silently discarded The registration time may be limited to a minimum and maximum time Limiting the minimum registration time avoids too many refreshes which cause network overhead Limiting the maximum registry time reduces the danger of
7. 7 T TCP threshold 39 Transfer 9 Transport Layer 16 29 U UAC 32 UAS 32 Uninstalling 23 User 59 User Agent 11 59 V VLAN 7 VoIP 7 W Web Access 16 Wildcards 46 snom technology AG e 71 snom technology Aktiengesellschaft Pascalstr 10E 10587 Berlin Germany Phone 49 30 39833 0 mailto info snom de http www snom de sip info snomag de 2002 snom technology AG All rights reserved snom USA Representation ABP International Inc Crestside Dr Coppell Texas 75019 USA Phone 1 972 831 0280 sip usa snomag de mailto usa snom de VoIP phones
8. There are several pages that give you detailed information about the proxy s state Registered Users To see which users are registered at the proxy you can go to Status Registered Users You will see a list of the users sorted by account name and probability On top you see the current time in Greenwich Mean Time GMT The columns have the following meaning e Name The name of the user as given in the registration e User The account that is used as identification in the proxy This corresponds to the telephone number of the user within the proxy realm e Registrar The registrar the user registered on This is one of the names listed in the hostnames e Contact This field has two components One is the path used to route requests to the destination the other the contact where the user can be reached The path is optional e User Agent The user agent identification tells the proxy if a license is required e Probability The probability of the registration Users are searched according to their probability snom technology AG e 59 snom 4S Proxy REGISTRAR MANUAL e Expires The expiry time in seconds If you click on the link behind this number you get to the SIP message trace that is associated with the registration e Delete If you click on the symbol the registration is removed This is helpful if you want to manually remove a registration otherwise you would have to wait until it expired R
9. a stateless proxy that transports SIP messages between private and public networks This makes it possible to share one public Internet address amongst several SIP elements The NAT gateway supports e Forwarding of RTP packets Both incoming and outgoing packets may be forwarded by the NAT gateway The SDP attachments of SIP messages are patched according to the local ports This allows usage of the NAT gateway together with a firewall e Path registrations Registration messages passing the proxy are tagged with the proxy path e Default destination Packets destined for the NAT gateway may be forwarded to a fixed address This way a publicly accessible proxy may reside inside a private network e PPPoE device support In Linux the NAT gateway automatically detects the public IP address and changes the address when the PPPoE device changes the IP address e Assignment of RTP port range To comply with available firewalls a range of ports may be assigned e Codec preference reordering The available codecs are reordered according to their bandwidth requirements This reduces the bandwidth used when talking over the NAT gateway and makes usage in DSL environments easier e Linking to Linux ipchains This way packets destined at SIP port 5060 can be redirected to the NAT gateway without setting up the user agents in the private network 16 e snom 4S Framework snom 4S Proxy REGISTRAR MANUAL Media Server There are situations
10. a user agent being unreachable for a longer period of time Typical values for minimum and maximum times are 30 seconds and 7200 seconds two hours Default Q When a user agent registers with the proxy it should indicate the probability with which the contact can be found at this address This value control the sequence in which the proxy searches for a user see sequential forking For instance a mailbox would register with the proxy with a low probability a softphone would reregister with a lower probability value when the screen saver goes on In this field you can define which value should be taken if no such value has been specified The value must be in the range between 0 0 and 1 0 A good value is 0 5 or 1 0 Reject Registrations Across NAT When a user agent registers it provides a contact and a path that tell the registrar how the user agent can be reached If the packet goes snom technology AG e 39 snom 4S Proxy REGISTRAR MANUAL through NAT aware equipment the proxy will get not only the private address but also the qay to get there see the Path header When a user agent from a private address registers without a path at a public address the registration will fail in most cases Unfortunately the registration is shown in the list of registered users but the registration response never made it back to the user agent This annoying effect can be avoided by turning the flag on The proxy will then not acc
11. are Manages 4 Starks and Installs re Provides s Provides s Started Started Started Started Started Started Started Started Started Started Started Started Sets the co Manual Automatic Automatic Disabled Automatic Automatic Automatic Manual Manual Automatic Automatic Aubormatic Automatic Manual Manual Manual Manual Manual Automatic Manual _ Manual snom technology AG LocalSystem LocalSystem LocalSystem LocalSystem LocalSystem LocalSystem LocalSystem Localsystern Localsysterm LocalSystern f LocalSystem LocalSystem LocalSystem LocalSystem LocalSystem LocalSystem LocalSystem LocalSysterm Localsystem LocalSystem LocalSystem 23 snom 4S Proxy REGISTRAR MANUAL Linux Installation Manual Starting If you just want to try the proxy it should be enough to start the proxy manually Load the tarball to a directory of your choice and start the proxy with the command proxy You can use the command line arguments shown in the next chapter You don t need to have root permissions to run the proxy in this mode normal user rights are enough Automatic Starting If you want the proxy to be started automatically after a reboot you need to set up some files as a root Make sure that you are logged in as root and go to the directory where you want to put the proxy This Figure 4 7 Accessing the Proxy Registrar with a Web Browser i snom 45
12. code like 401 does not mean the end of this call the proxy does not differentiate between ongoing calls and failed calls Therefore all non finished calls are kept in the list of pending calls The web server displays the pending calls in the same fashion as the finished calls If you want to see the packet history associated with the calls just click on the link shown in the web interface Call Log File Format A line in the call log file has the following format Start time Seconds Duration From To The start time is separated by a colon from the rest so that it is easier to parse the log file automatically The date itself has the format Weekday Month Date Time Year with the time in the format hour minutes seconds An example would be Fri Jul 5 16 17 06 2002 The duration of the call is given in seconds The from and to addresses are taken from the From and To URL in the headers of the INVITE packet If the hostname in the URL match the hostname the proxy is responsible for they are stripped from the URL This makes the log easier to read 62 e Maintenance snom 4S Proxy REGISTRAR MANUAL SIP Message Flow Should a problem occur a look at the messages that went though the proxy can be very helpful If you go to the Trace web page a list of the last messages appears on the screen The list has the following elements e Type The type indicates whether the packet was received R or trans
13. finished The user needs to click on cancel Shutdown of the whole system also works TLS transport layer needs to be supported When the user does not have sufficient administration rights the proxy does not register it This can be a problem when the proxy needs to be restarted as the registration information may not be saved however in this case the proxy recovers after the maximum registry time HTTP port setup The http port of the proxy must be entered during setup If the desired port 80 is not available the proxy tries port 5068 5069 and on This behaviour needs to be optimized in future releases Where traffic is heavy the call log may miss a call This happens when the number of open calls exceeds the proxy s capacity limit 200 calls and the opened call did not receive a 200 Ok on BYE Making the call log safe requires usage of session timer in the proxy Authentication for the web server is only Basic This limits the security of the web access DNS NAPTR is not supported Only DNS SRV and DNS A are used All time statements refer to GMT This should be changed to local time in some cases for billing purposes for example Standards The standards used for this proxy are open in the sense than not only snom is using them Feel free to take a look at the underlying standards General web page for standards http www ietf org internet drafts SIP working group drafts http www softarmor com sipwg drafts and www softa
14. is triggered This is typically the case in USA e Where the length of a telephone number cannot be determined beforehand the network responds with number incomplete if more digits are needed to start the call This mechanism is called overlap dialing The same problem occurs when the user enters a SIP URL Even if the URL contains alphanumeric characters overlap dialling can be done in SIP For this the response code 484 was defined in the SIP standard The proxy responds with this error code when the number detected could not be completed by the PSTN gateway or by the proxy Sequential Forking Forking means that a user may be registered several times and the proxy searches the user on all locations For non INVITE requests not initiating a call the proxy just sends the packet to all destinations and waits until all parties have sent a response or a success response arrives For INVITE requests initiating a call the proxy searches the user according to the probability Users that registered with a high probability are called first and then users with a lower probability When users have the same probability they are called at the same time this is called parallel forking When users have different probabilities they are called in a row this is called sequential forking When the proxy receives a 3xx response redirect it handles them in a special way If there are other requests pending it determines 30 e General C
15. to an open question If that is the case the request passes if not the proxy generates another question snom technology AG e 27 snom 4S Proxy REGISTRAR MANUAL The answer depends on the realm the username and the password stored in the proxy and in the user agent By looking at the answer it is not possible to find out anything about the password or username The setup process is important in ensuring security When you use a web browser to set up usernames and passwords this information is transported without security over the network You should therefore follow the following guidelines e Using a password on web interfaces does not help because the data transported is not encrypted using this mechanism If you open a web page that contains the password it will also be transported over the network without encryption e The realm and the usernames are no big secret But make sure that passwords are not sent over insecure parts of the network On a phone you can set up the password using the phone keyboard for the proxy you can use the loop back device 127 0 0 1 for the setup process if you are logged on the proxy host Reliabilty Proxy failure It is a fact of life that computer systems can crash Some precautions can limit the damage The general approach to address failure is to use redundancy If one computer fails for one day a year two might fail only for a couple of minutes SIP supports redundancy wit
16. Administrator s Manual VoIP phones snom 4S Registrar Proxy Version 2 20 User Manual 2002 snom technology Aktiengesellschaft All Rights Reserved This document is supplied by snom technology AG for information purposes only to licensed users of the snom 4S registrar proxy and is supplied on an AS IS basis that is without any warranties whatsoever express or implied Information in this document is subject to change without notice and does not represent any commitment on the part of snom technology AG The software described in this document is furnished under a license agreement and may be used only in accordance with the terms of that license agreement It is against the law to copy or use this software except as specifically allowed in the license No part of this document may be reproduced republished or retransmitted in any form or by any means whatsoever whether electronically or mechanically including but not limited to by way of photocopying recording information recording or through retrieval systems without the express written permission of snom technology AG Welcome to the SIP World SIP is becoming more and more accepted in the area of VoIP Many companies are working on SIP solutions and making great products that will make telephony much easier and better SIP without a proxy makes no sense Entering IP addresses to find another user cannot be the future of telephony Locating http web content an
17. GISTRAR MANUAL out when all attached SIP devices use the latest SIP draft for generating URLs The destination will be the dialled number plus the string gw which would be the gateway in this installation Rules 2 through 4 match destinations with 1 to 3 digits They are marked as incomplete giving the user the chance to enter more digits Example 2 North American Dial Plan This example is suitable for a proxy located in the USA Rule Mode User Pattern Destination Group Use Gateway sip 911 sip 911 gwl Use Gateway sip 1 9 sip user gw2 4 Use Gateway sip O 1 sip user gw2 9 0 Use Gateway sip 00 r sip user gw2 Rule 1 defaults all calls not for registered users to incomplete Rule 2 redirects all emergency calls to the gateway number one which could be connected a local analog line Rule 3 redirects local calls 7 digits not starting with 0 to the second gateway rule 4 does this for national calls a prefix of O indicates a national call International calls start with two Os and get redirected in any case to the gateway this works only if the gateway is able to generate incomplete responses Example 3 Do not allow cell phone numbers to certain users In this example only certain users may call cell phone numbers 400 499 and 101 This example makes sense if the users 101 and 400 499 are listed in the well known user list in the User Management lis
18. Messenger Optionen GI Personliche Angaben Telefon Einstellungen Privatsph re Konten Yerbindung zuerst uber dieses Konto anmelden NET Passport Communications Service MET Passport Konta Ncht angemeldet nat Meine Kontaktliste enth lt Benutzer von NET Messenger Service Communications Dervcekonio Gngemeldel 3 Meine Kontaktliste enthalt Benutzer eines x eg Eommunikationsdienstes Benutzername strtsromag de snom technology AG e 57 snom 4S Proxy REGISTRAR MANUAL You then can make your first test call The snom 4S Proxy Registrar supports presence and instant messaging with the Microsoft Messenger Just enter the contact that you would like to see the proxy will handle the traffic to the registered Microsoft Messenger client Important Turn loose routing off when using the Microsoft Messenger This is done by default Figure 7 3 Selecting Server and Transport Communications Service Verbindungskonfiguration St Wahlen Sie die Methode aus mit der Ihre Verbindung zu einem Eommurnikationsdienst konfigurert werden soll Automatische Konfiguration Einstellungen konfigurieren Servername oder IP Adresse 192 168 0 1 Verbinden uber C TCP ere UDP 58 e Registering Phones Maintenance Once the proxy is up and running you will probably want to take a look on what is going on
19. acket Trace NOTIFY sipirm snomag de SIP 2 0 Va SIP 2 OfUDP 217 115 141 99 5064 branch 29hG4hkK od6bgwddwarg Max Forwards 70 From lt sipirm snomag de gt To lt sipirmm ei7 115 141 99 5064 gt Call ID Of00923d1809 ymytzbdeqq9z 217 115 141 99 Seq 35 NOTIFY Event message summary Contact lt sipirm 217 115 141 99 5054 gt Content Type application simple message summary Content Length 38 Message Malting yes Voicemail 1 1 The proxy actually keeps more messages than are displayed on this list This is necessary because it may take some time until the user clicks on a specific packet and the proxy does not know when the old packets are no longer needed If you have a lot of packets flowing 64 e Maintenance snom 4S Proxy REGISTRAR MANUAL through the proxy it might be that older packets are no longer available However the packets are kept in the call flow analysis log and on the registration page Logging If you want to see the log file just go to the Log file menu item To clear the log go to the bottom and click on Clear Logfile 7 Mon Oct 7 14 29 53 2002 Updating gw snomag de to gw 192 163 195 252 5060 7 Mon Oct 14 30 00 2002 Updating rm snomag de to rm 217 115 141 99 5064 7 Mon Oct 14 30 00 2002 Updating np snomag de to npm ei 115 141 99 5064 7 Mon Oct 14 30 02 2002 Updating infomsnomag de to infomet 115 141 99 5064 7 Mon Oct 14 30 02 2002 Updating cs snomag d
20. after 27 s If someone picks up the call the others will stop ringing immediately 42 e Configuration snom 4S Proxy REGISTRAR MANUAL Domain Administration The proxy keeps a list of domains which it is responsible for These domains are kept seperate from each other This makes it possible to use the proxy for different domains which should not share information This makes the proxy usable for small Internet service providers which want to offer SIP services to their customers A domain is made up by its primary name and a list of alias names Within the alias list and the primary name it is possible to call users For example if the primary domain name is cablecat org and the alias are sip cablecat org and www cablecat org a user registered as abc cablecat org can be called by the names abc sip cablecat org and abc www cablecat org The default domain of the proxy is the domain list you entered during the licensing of the proxy This list cannot be deleted and is the default when you don t enter a domain name in other parts of the proxy Domain Administration Domain Alias Edit Delete cablecat org sip cablecat org Ss snomag de 217 115 141 99 snom cam x www snomag de Add Edit Domain Alias snom technology AG e 43 snom 4S Proxy REGISTRAR MANUAL User Administration The well known users of the proxy may be challenged on registration and on forwarding requests This way you can ensur
21. ant to select Licensing Before you start operation you need to set up the licensing part of the proxy To do this go to the Administration Licensing web page and enter the host names the IP addresses of the proxy if not proposed correctly and the license key that you received with the software If you don t have a license key contact mailto support snom de for one After saving this page the license type and the number of currently registered users is displayed on top of the page snom technology AG e 33 snom 4S Proxy REGISTRAR MANUAL Current license type Professional Maximum number of user agent registrations 3500 Number of currently registered user agents 60 License Setup The hostnames are the names the proxy feels responsible for Enter a list of space seperated names e g proxy company com proxy company net 123 123 123 999 The proxy will forward packets that are not destined to one of the hostnames on this list If you dont have a license key please contact supportasnom de Hostnames snomag de 217 115 141 99 snc License key snom proxy exp fd9aaedce235 Hostnames You need to enter a list of names that the proxy feels responsible for When a packet arrives at the proxy the proxy checks the given hostname against the list you enter in this field Typically this name contains a list of all fully qualified DNS names for the host e g rumba company com sip company com company com compan
22. any more bits to identify a host but this is much harder to implement and maintain so NAT is still more popular Routing SIP messages flow from a user agent the user agent client UAC through a number of proxies to another user agent the user agent server UAS This creates a path the routing path that needs to be remembered for further messages For instance if a proxy wants to carry out billing it needs to see all messages between the user agents to determine how long the call took To do this a proxy can insert a header into requests that indicates that it would like to stay in the routing path in future requests Unfortunately the first proposals for doing this did this in a complicated way that can cause problems under certain circumstances For this reason loose routing a new and better way of routing messages was developed The snom 4S supports both routing methods 32 e General Concepts Configuration The proxy can easily be set up via a web browser To access the proxy just enter the name of the computer where the proxy is running If you have configured the proxy to use a port other than 80 you will need to append the URL with a colon and the port number e g http proxy mycompany com 5069 You can access the different menu items of the proxy by moving the mouse over the top level menu items Administration and Status Move the mouse over the pop up menu items and click on the item you w
23. brief introduction to VoIP and SIP explains the installation process for Windows and Linux and shows how snom technology AG 3 snom 4S Proxy REGISTRAR MANUAL to run the SIP proxy For additional snom 4S information please visit our Web site at http www snomag de and if you have any comments and Suggestions about snom 4S please contact us through snom technology AG s support link Web site We would appreciate your feedback And of course you can reach us at sip info snomag de Thank you and have fun using the snom 4S Dr Christian Stredicke Nicolas Peter Pohland 4 e Welcome Table of Contents WEICHEN EE 3 The Voice over Internet Protoco0l uuuusuuuununnnunnunnnns 7 Ve a a EEEE AE ERAEN 7 Open Stan Gal e CEET 8 What You Can Expect and What NOE eege tege Eed 9 The SIP Architecture EE 11 USER AGENT ee ee AE 11 Bert 12 Beeler Ee 12 POO Se en E rer EE E E dade annua 12 Media EE 13 LGW GY EE 13 snom 4S Framework uusuunnnnunnnnnnnunnnnnnnunnnnnnnnnnnnnnnnn 15 POX orana EAEE Teen 15 SIP NAT SG EN 16 Media EE 17 INStalauOR een nnd 19 Windows Installation TE 19 Uninstalling in WINdOWS ee ee 23 Linux Installation E 24 General e Ev EE 27 SEENEN 27 ts e EE 28 Se EE 29 Overlap DIS e ee 50 Sequential Forking WEE 30 Network Address Translation EEN EEN KEEN nun 31 Seit gtt MEN Ee snom technology AG e 5 snom 45 Proxy REGISTRAR MANUAL Beleg Le ea nennen 33 Briefe ee een een 33 Gene
24. cept when otherwise stated in writing the copyright holders and or other parties provide the program as Is without I do not accept the terms in the license agreement InstallShield 20 e Installation snom 4S Proxy REGISTRAR MANUAL a temporary directory It is important that the directory exists the proxy will not create this directory In the next step you can select the installation type We recommend using the Typical installation If you select Minimal the documentation is not installed Before the installation finishes you need to define on which ports the proxy will operate This is important because otherwise it will be hard for you to find the right port The http port defines where the web server of the proxy can be accessed The default port for web servers is 80 and if you are not running any other web services on the computer port 80 is a good choice Otherwise choose a free port and write the port number down somewhere Figure 4 3 Installation Customer Information iy snom 45 Proxy Registrar InstallShield Wizard EN Customer Information sn om Please enter your information YolP phones User Name Fred F Feuerstein Organization Stones Bricks amp Bones Inc snom technology AG e 21 snom 4S Proxy REGISTRAR MANUAL Figure 4 4 Installation Port Definition snom 45 Proxy Setup http port default 80 5068 SIP port default 5060 5060 You can access the the prox
25. cipant and also notifies them of participants joining and leaving the conference The conference server also checks the credentials of participants joining the conference The snom 4s is an example of this technology Gateways From a SIP perspective the gateway is also just a user agent Instead of playing the audio stream on a speaker it sends it to the PSTN network and instead of getting voice from a microphone it retrieves Signals from the switched network There are three kinds of gateways PSTN proxy signalling and NAT gateways Depending on the nature of the gateway it may serve one two four thirty sixty or more channels at the same time Other gateways may translate the signal to existing H323 networks or other proprietary technology networks These gateways are sometimes called signalling gateways snom does not produce SIP gateways Examples of such gateways are manufactured by Cisco snom technology AG e 13 snom 4S Proxy REGISTRAR MANUAL Mediatrix Sonus and Vegastream The snom 4s gateway is a SIP NAT gateway software enabling Linux computers to be SIP aware 14 e SIP Architecture snom 4S Framework snom has set up a SIP based solution targeted at small and medium sized installations This solution may be installed on Windows as well as on Linux computers The registar proxy is the core part of this framework Proxy The snom 4S registrar proxy is a SIP registrar and proxy with the followi
26. d 493 Undecipherable The message attachment could not be decoded 500 Server Internal Error This is a generic network failure message feature is also quite a generic error message 505 Version Not Supported There is a problem with the SIP version used 513 Message Too Large The message is too large to be processed snom technology AG e 51 snom 4S Proxy REGISTRAR MANUAL 600 Busy Everywhere There is really a big problem and something for the system administrator 603 Decline A network element refuses to work at this time 604 Does Not Exist The requested resource does not exist anywhere Anywhere 606 Not Acceptable Some aspects of the SDP record are not acceptable e g bandwidth or addressing style This is also something for your network administrator Welcome Message When a new user signs in the proxy may send him or her a welcome message This is a nice feature that informs users about the operators capabilities or downloads operator images onto the phones When the location of the attachment file changes the proxy notifies all registered users about the change Welcome Message Method MESSAGE Event Content Type text plain Attachment File home stredich pry proxy wel The proxy allows two method for notifying users message and notify Notify is typically used for sending media attachments message is the instant message notification style which is compatible with most popular equipme
27. d finding email users has become a part of todays communication behavior and sure will be part of telephony in the near future However for the small and medium size office we are missing a simple yet powerful solution that is available for a standard software price That is why we are making this simple and straightforward proxy available snom 4S stands for snom soft switch for small and medium enterprises That means the snom 4S proxy was designed for environments handling up to 1000 users with normal traffic In environments where you need more features and better scalability we would be happy to refer you to other companies offering carrier grade and feature rich proxies that solve these problems This product is a proxy locations server with built in registrar which means this software is responsible for locating users Features like follow me and group calling are therefore supported however media services like mailbox and music on hold are not part of the software You should use a media server for this Interoperability is important to us We have tried to stick to the SIP standard as well as possible and tested the phones of other vendors We hope that this will help to build up a flourishing VoIP telephone industry in which the products of the different vendors work together like the products in the computer industry do today We believe that having a choice is good for you and therefore good for us This manual gives you a
28. e TCP packets State The snom 4S SIP proxy handles stateful information This is information that needs to be stored somewhere until another event happens This information primarily affects registrations as they might be refreshed only after hours or even days It is therefore important to store this information in a safe place which will be stable even after a crash or reboot The use of redundancy to make file systems more resilient is a proven solution in these cases There are several solutions available here and the snom 4S builds upon these mechanisms Registrations may be stored in a safe place and stateful information may be recovered by reading it from the file system Other stateful information is less critical When forking a request there needs to be some state information about the fork However because this information usually has a scope of only a few seconds this information is not stored in a separate database In a case of a reboot the complete system will recover fast enough snom technology AG e 29 snom 4S Proxy REGISTRAR MANUAL Overlap Dialling When a telephone user dials anumber she or he does not have to press enter to start the call in a traditional telephone system There are two ways to achieve this with the snom 4S e Where the length of a telephone number can be determined by a simple rule a dial plan is used When the entered number matches a set of pattern the dialling process
29. e for this field is 1300 Using this value a UDP packet can be sent within one Ethernet frame without fragmentation Log Level The log level defines how many messages get to the log If you are only interested in the most important messages you can set this to 0 If you want to see any possible log message set this field to 9 The log is kept internally within the proxy After a certain number of log entries have been reached the oldest entries are removed from the log so that there is no danger of memory overflow from files getting too large HTTP port The http port is used to contact the web server of the proxy If you can see the configuration page you have found the right port However sometimes you might want to change the port number to a different value e g to install the mailbox In this case enter the desired port number here and restart the proxy HTTP User and Password To protect the access to the web server you can set up a user name and a password for the web server Remember that this provides snom technology AG e 37 snom 4S Proxy REGISTRAR MANUAL only basic security as the content of the web page is transmitted without encryption over the network and the passwords can easily monitored by network specialists However it avoids everybody easily accessing the proxy Registration Registrar Settings Require Authorization C on off Trace REGISTER C on off Save Registrations to
30. e that users are really who they claim to be and give them special rights e g to make international calls User accounts can easily be set up with the web browser Just go to User Administration and add new users To delete users click on the delete button of the respective user If you dont specify a domain the proxy will use the default domain of the proxy which you entered during the licensing of the proxy The user account is the part that occurs in the URL The user name and the password are requested during authorization They Should be kept in a secure place and set up on the local machine avoiding the sending of passwords over the network User Administration Domain Account Username Password Edit Delete intern snorn de 101 101 E S d intern snom de 10 102 rt S A intern snom de 103 103 KERR z A intern snorn de 104 104 PEE d intern snom de 111 111 Pt d intern snorn de 120 120 Er S d intern snom de 121 121 EEE zZ A intern snorn de 147 147 Here S d intern snom de 200 gt 00 ki Sg A intern snom de Sek SE Sc d intern snom de 320 320 HERE Ss A intern snom de 2320 330 St SN A intern snom de 401 401 PERF A intern snom de 410 410 Si A intern snom de 421 421 Ee S A intern snom de 422 427 E d intern snom de 423 423 Va F A intern snom de 424 424 rt I A To load a large number of users at one you may use the Load from File feature The file that you select there needs to be
31. e to csm217 115 141 99 5064 7 Mon Oct 14 30 02 2002 Updating canf snomag de to conf 217 115 141 99 5064 5 Mon Oct 14 30 20 2002 Opening new request 0 open INVITE sip l snomag de SIP 2 0 7 Mon Oct 14 30 23 2002 Updating ne snomag de to nem 195 242 54 243 7 Mon Oct 14 31 15 2002 Updating tw3 e217 115 141 99 to tw3 24 54 160 32 5060 5 Mon Oct 14 32 00 2002 SIP port accept 7 Mon Oct 14 32 00 2002 Updating hm snomag de to 134 108 35 5 14220 7 Mon Oct 7 14 32 09 2002 Updating 422 snomag de to 4220192 168 188 234 5060 7 Mon Oct 14 32 10 2002 Updating ag snomag de to agm i92 168 188 234 5060 1 Mon Oct 14 32 15 2002 Remove registration for xslpiest e1 68 118 117 10395 line 1 srcadr 192 168 0 3 345060 gt file froot registrations cst snomag de J000000bedco 2dpbiclhynybsy 192 168 0 3 7 Mon Oct 14 33 00 2002 Remove connection to 134 108 35 5 39940 5 Mon Oct 14 34 18 2002 Opening new request 0 open SUBSCRIBE sip 496 snomag de SIP 2 0 7 Mon Oct 14 34 42 2002 Updating htnaome1 115 141 99 to htnaom e4 53 110 87 10006 7 Mon Oct 7 14 35 19 2002 Updating kw snomag de to kw 192 168 197 227 5060 snom technology AG e 65 snom 4S Proxy REGISTRAR MANUAL 66 e Maintenance More Information Open Issues The following issues are open or pending Manually stopping the proxy in Windows Service Manager works but does not signal the service manager that it has
32. egistered Users at Mon 07 Oct 2002 17 11 17 GMT User Name User Registrar Contact Prob Expires Delete Agent a intern snom de lt sip 0 192 168 195 254 5060 line 7 gt Hr 4003076 X a intern snom de lt sip 0 192 168 195 252 5060 line 7 gt EE x Maria o intern snom de lt sip 0 192 168 195 253 5060 line 5 gt E S02 750 A 101 intern snom de lt sip 101 192 168 197 218 5060jline 1 gt SOMIOO 1 000794 X 101 intern snom de lt sip 101 192 168 0 44 5061 line 3 gt Gr Call Logs Condition for Logging a Call A call is logged when the following conditions are met 1 The proxy received an INVITE and forwarded the request successfully 2 Then the proxy received a 2xx class code on this INVITE This defines the start time of the call 3 The proxy receives a 2xx code on a BYE for this call This defines the end time of the call A call gets into the call log as soon as the start time and the end time have been determined The number of open calls is limited to 500 60 e Maintenance snom 4S Proxy REGISTRAR MANUAL calls so if more than 500 calls have been started but not finished the proxy cannot close a call and the call will not appear in the call log This is to limit the amount of memory used for call logging Call Logs in the Web Interface To see the calls that went through the proxy you can go to the call log page The call log has the following fields e Date Time The date and time when the call started in GMT
33. ept private IP address registrations if they have a public address and if there is no path provided with the registration Instead it will write a log entry Routing Routing Settings Protected Destinations Max forwards 10 Call Log File arlog sip calls log MAT Gateway Do not signal loose 3 ont routing iio SE Do not Record Route if mon amp Route is present on oif Remove tags on 18x e ve codes on fr off Sequential Fork Time Sie ei Protected Destinations When the proxy needs to forward a request it first checks this field for protected destinations If one of the destinations match the requested URL the proxy first challenges the client for authentication 40 e Configuration snom 4S Proxy REGISTRAR MANUAL The protected destinations are seperated by space and contain a pattern according to the rules described in the Dial Plan see below Typically you want to protect access to the PSTN because this requires payment For example if your PSTN gateways are located at 192 168 0 248 and 192 168 0 249 and the dial plan starts using the PSTN gateway after 4 digits you would enter a pattern like sip sip 192 168 0 24 8 9 The first pattern makes sure that every request that would be redirected to the PSTN gateway is challenged the other patterns make sure that direct access to the PSTN gateway is challenged If you leave the field blank the proxy will forward any packet w
34. eptable There was an unacceptable parameter this is a generic error message 407 Proxy Authentication This is like 401 Required 408 Request Timeout The destination did not respond at all Probably it has been switched off 50 e Configuration snom 4S Proxy REGISTRAR MANUAL 410 Gone The destination is switched on but the requested account is not there 413 Request Entity Too The request was too large for the destination Large hardware 414 Request URI Too Long Type media standard Scheme URI scheme e g Sips destination the caller request 480 Temporarily Unavailable The requested destination is temporarily unavailable and more detailed information is not available 481 Call Transaction Does The request refers to a request which is unknown Not Exist at the destination 482 Loop Detected The request could not be forwarded properly 483 Too Many Hops Same as 482 484 Address Incomplete The address is incomplete more digits are required to complete the call 485 Ambiguous There were several possibilities for finding the destination and the destination was not able to determine which one should be the destination 486 Busy Here The destination is busy 487 Request Terminated The request has been terminated by a CANCEL or BYE request 488 Not Acceptable Here Cannot be accepted this is a fairly generic message 491 Request Pending There is another request pending so the current request cannot be processe
35. f in doubt it is better to turn this flag on Do not Record Route if Route is present Some old equipment does not like to see both recorded routing elements and an already available route path in the SIP header at the same time In these cases it might help to switch this flag on however the price of this is that the proxy is probably not in the route of future requests any more This means you will not be able to see a proper call log even if the phone calls have been successfully made Remove Tags on 18x Some equipment cannot handle different To tags coming from forking INVITE requests If you turn this flag on the To tags on 18x replies are removed before they are passed down to the user agent client Typically you will not need to turn this flag on Sequential Forking Time The proxy needs to schedule the sending of INVITE requests This is done by looking at the user with the highest probability for the call and scaling the other users according to this probability and the sequential forking time This setting defined the time between the first ringing of a user agent and the maximum time in seconds until the last user agent rings For example if there are three users for number abc with the probabilities 0 9 0 5 and 0 1 and the sequential forking time is 30 seconds the contact with probability will ring immediately the contact with probability 0 5 after 30 x 0 9 0 5 0 9 13 s and the contact with probability 0 1
36. h the DNS SRV model Behind a DNS address there may be several IP addresses each of them pointing to a different proxy If one fails the user agent goes to the next proxy and the service goes on Terminal Failure When a terminal fails because of power failure network disconnection or other events the other side might not get a disconnection message This can be a problem for media server and billing programs For this purpose the session can be periodically refreshed This is called 28 e General Concepts snom 4S Proxy REGISTRAR MANUAL Session Timer Depending on the refresh rate of the timer the timing for billing purposes for example can be made very accurate Transport Layer SIP today uses UDP as main transport layer Unfortunately it is perfectly legal that UDP packets get lost on their way to the destination Because of this the SIP programs must retransmit their UDP messages until they receive a feedback that the message has been received by the other party This can cause problems when large packets are being transmitted In most networks large UDP packets are split up into several smaller packets which are transmitted independently and which have their own individual chance of getting lost To avoid this the latest SIP Standard recommends using a different transport layer for this TCP The snom 4S proxy supports both transport layers and automatically detects whether an old SIP device cannot handl
37. ilt upon the same principles used by http and email Moreover it has found an enthusiastic community of researchers and developers who like the idea of applying Internet technology to real time communications More and more applications are being put into SIP telephony being just one of them So far more than 150 drafts have been proposed for extending the SIP protocol All kinds of solutions are being addressed in these documents and the highly dynamic field of this new real time communication technology is resulting in evolutionary pressure to find the best common denominator Most of the big players have jumped on the SIP train Microsoft Messenger is based on SIP and Cisco Systems offers SIP extensions to most of its products International organizations like ETSI host SIP interoperability events and next generation mobile technology will be integrated with if not based on SIP see the 3GPP for more details Open Standards Open standards define the rules of the game Interoperability allows customers to choose between the products of different vendors and opens up competition below the system level This can be advantageous for the customer as the computer hardware industry has shown Many vendors therefore advertise their usage of an open standard defining this term as we make the way our standard works public However this cannot really be called standard if only one vendor is using it The disadvantage
38. in a simple ASCII format as follows 44 e Configuration snom 4S Proxy REGISTRAR MANUAL Each line describes a user The first entry defines the domain the second the account the third the username and the fourth the password The entries are seperated by whitespace Comment lines can be set up by using a at the beginning of the line Loading accounts from a file erases all accounts that have been set up so far Load from file You can load a complete list of known users directly from a file For every user the file contains a line with the account name the user name and the password seperated by whitespace Filename Durchsuchen Dial Plan How it works The dial plan is a flexible way to tell the proxy what to do with calls that do not go to a registered user The algorithm for checking the dial plan is simple e Determine the source user group by looking at the From header of the request take only a look at the URL provided there e Determine the destination by looking at the request URL e Go through the dial plan and take the last match found as result if there is no match allow the request Checking the user group limits the pattern to a specific list of users This way you could for example grant the sales people the right to make international calls while everybody else is limited to local calls snom technology AG e 45 snom 4S Proxy REGISTRAR MANUAL Looking at the destinati
39. ipment can already fulfil this real time requirement Virtually all switches currently on sale support a VLAN with different priorities in the network and the vast majority of higher layer network equipment supports some means of transporting packets with different qualities DiffSrv The LAN usually supports a bandwidth of 100 MBit s which is more than enough to allow voice to flow through the network and adherence to a certain set of rules ensures that this bandwidth is enough to supply superior telephone quality The Internet backbone s ability to transport large loads is increasing on a daily basis and global communications are now ruled by the Internet Why SIP There has been a protocol war regarding the best way to set up a phone call In the mid 90s H 323 was the first attempt to unify the VoIP industry under a common standard and move the world of telephony into the computer industry using most of the methods known from ISDN Seen however from today s perspective the resulting technology was snom technology AG e 7 snom 4S Proxy REGISTRAR MANUAL far too complex so products based on this technology did not work well together The late introduction of supplementary services H 450 x not only introduced another level of complexity but was also simply too late By the late 90s the Session Initial Protocol SIP had been proposed RFC 2543 SIP follows the paradigms of the Internet and is bu
40. is that customers still have a limited choice of products they can buy There is no one objective definition of an open standard However something approaching an open standard could be reached if a significant number of vendors offered products using the same standard giving customers the possibility of combining products to create a system SIP is just such a standard 8 e About VoIP snom 4S Proxy REGISTRAR MANUAL What You Can Expect and What Not Telephony is more than making calls from A to B SIP supports all kinds of transfers call parking and call picking user searches Follow me mailbox support and all the other features known from traditional telephony In addition to this telephones can now indicate their willingness to receive calls and the probability of finding a specific user You can call a PSTN number from a SIP phone just as you did ten years ago The network will usually be set up to terminate these calls on a gateway which translates the packet stream into a switched network signal You can also dial email like numbers like sip fred flintstone megaportal com and you can reach your sales team under the same telephone number and email address Internet telephony is still a best effort communications technology and does not always necessarily support the quality of transport telephony requires If you are placing a phone call over the public Internet there is no guarantee that a packet will be tran
41. ithout challenging If you enter just the proxy will challenge every request Max Forwards Messages in SIP may hop over a number of proxies and sometimes the path contains loops Sometimes the loops are endless and in these situations the criterion for rejecting a message is to look at the number of hops the request has done so far This setting controls how many hops a request can make before it is rejected as an endless loop 70 is the default value in many environments you can significantly lower this value Call Log File Calls may be logged to a file If you enter a file name here the proxy will try to append a line for every call that went through the proxy See Call Log File Format below for the content of this file NAT Gateway Other calls need to pass through a network address translation NAT gateway or a firewall The criterion for this is when the proxy is ina private network address space and the destination is a public address The NAT gateway setting has the same format as the PSTN gateway setting snom technology AG e 41 snom 4S Proxy REGISTRAR MANUAL Do not signal loose routing Although loose routing is mandatory for new SIP equipment and is compatible with the old routing method strict routing some equipment can still cause headaches You can use the old style routing by turning this flag on If you know your equipment does not have a problem with loose routing turn the flag off I
42. ke sure that the proxy is running after the reboot After making sure the proxy is running you should connect to the proxy to a web browser In order to do this you can connect to the address of the local computer http 127 0 0 1 8080 if you are running the web browser on the same machine If the http port is already occupied by other programs the proxy will try to use ports 5068 5069 5070 and so on It is important that you connect to the proxy to a web browser because that is the only way to control the proxy Uninstalling in Windows To uninstall the proxy first stop it in the services window Then go to the Software Window and click on remove for snom 4S proxy Server Figure 4 6 Services in Windows Services Local 884 Remote Procedure Sa Remote Registry Se 8 4Removable Storage i Ss Routing and Remot Funds Service l Sia Security Accounts Server 884 smart Card E fy Smart Card Helper E snom 45 SIP Proxy j ity System Event Motifi Sa Task Scheduler Sa TCP IP NetBIOS Hel K Sia Telephony 4 Telnet 4 Sa Uninterruptible Pow if Sa Ltility Manager d Sa Windows Installer I Sa Windows Managem i Sa Windows Managem _IBawindows Time __ Manages E Allows rem Manages t Offers rout Enables st Shores eer Provides R Manages a Provides s SIF Proxy N H Tracks systk Enables a Enables su Provides T Allows
43. mitted T By clicking on the symbol you get a list of all packets that have the same call ID as the packet e Source Destination Here you can see which transport layer UDP or TCP was used the IP address of the source or destination and the port that was involved e Header Here you can see the first line of the SIP message snom technology AG 63 snom 4S Proxy REGISTRAR MANUAL Packet Trace Type Source Destination Header Fr udp 2453 110 37 14363 REGISTER sip 217 115 141 99 SIP 2 0 Ta udp 24 53 110 37 10005 SIP 2 0 200 OK Re udp 65 197 57 216 5060 REGISTER sip snomag de SIP 2 0 Ts udp 65 197 67 216 5060 SIP 2 0 200 OK br udp 24 53 110 87 14368 REGISTER sip 217 115 141 99 SIP 2 0 Ta ude 2453 110 37 100068 SIP 2 0 200 OK Rs udp 217 80 21 184 5060 REGISTER sip snomag de SIP 2 0 Ts ude 217 80 21 134 5060 SIP 2 0 200 OK br ude 2453 110 87 14365 REGISTER sip 217 115 141 99 SIP 2 0 Ta udp 24 53 110 37 10006 SIP 2 0 200 OK Rs udp 2454 150 32 5060 REGISTER sip 217 115 141 99 SIP 2 0 Ts Ude 24 54 160 32 5060 SIP 2 0 200 OK Re udp 217 80 21 184 5060 Ts udp 217 50 21 184 5060 Ts udp 55 197 67 222 5060 Re udp 65 197 67 222 5060 Re udp 65 197 67 222 5060 Ts udp 217 50 21 184 5060 INVITE sipprm snomag de SIP 2 0 SIP 2 0 100 Trying INVITE sipirm as 197 67 222 5060 line 1 SIP 2 0 SIP Z 0 100 Trying SIP 2 0 180 Ringing SIP 2 0 180 Ringing By clicking on the header line you get the whole packet P
44. ng features e Stateful forking Requests are forked to one or more destinations and the responses are filtered before passing them back to the user agent client e Sequential forking Users are searched according to the probability that was provided with the registration e Full functionality All SIP methods are supported that includes transfers call parking call picking notifications instant messaging and other SIP features e Dial plan You can set up dial plans that will determine whether specific users may call specific destinations whether numbers are complete or whether numbers are to be redirected to one or more gateways e Authentication You can force clients to authenticate their identity e NAT handling Requests leaving the private network may be redirected to a NAT gateway e Support of path registrations This way user agents may register with a path that may contain proxies that must be passed e Failure recovery Even after a reboot the proxy keeps the state of the registrations snom technology AG e 15 snom 4S Proxy REGISTRAR MANUAL e TCP and UDP transport layer support Both unreliable and reliable transport layers are supported e Web Access The proxy can be managed remotely via a web browser e Interoperability The proxy is interoperable with the SIP equipment of other vendors you are not limited to snom products SIP NAT Gateway The snom 4S Network Address Translation NAT gateway is
45. nt While notify requires a event type message usually does not require an event type The content type indicates the type of the attachment The attachment file points to the location of the file what should be sent to the users 52 e Configuration snom 4S Proxy REGISTRAR MANUAL DNS What is DNS The domain name system DNS is a powerful mechanism to make internet addresses human readable www snom de is much easier to remember than 192 67 198 4 But there are also other reasons to use DNS If the underlying address changes the user does not have to change all the addresses in his or her address book If the address is often used it can redirect the requests to several servers server farm for load balancing If one server in a server farm fails another server can continue the operation One of the key features of SIP is that your email can be the same as your telephone number your marketing department and your friends will love it Setup DNS Using DNS has two sides Finding someone with DNS and being found with DNS Finding somebody with the proxy is easy All you need to do is set up the DNS on your computer correctly and the proxy will talk to the DNS server directly to find addresses Hint Both Windows and Linux offer standard DNS functions which are not enough for SIP DNS resolving Therefore the proxy contains its own DNS implementation that caches the entries on a private list The Windows version re
46. ny installations several computer and network elements have to share one IP address They do this by using different ports of the address An IP packet may go to one of 65 535 ports making up roughly 16 bits and extending the internet address to about 48 bits The computer that owns the IP address is called the network address translation NAT gateway This computer has one real IP address called public IP address and a private IP address that is visible only to the computers that share the public IP address in a private network The internet society has defined a specific address space that is used as private IP addresses 192 168 x x 10 x x x and 172 16 31 x x The NAT gateway keeps a list of ports and associated private IP addresses Whenever a packet arrives at the NAT from the public Internet the NAT gateway looks into the list and forwards the packet to the associated computer and port When a packet arrives from a private snom technology AG e 31 snom 4S Proxy REGISTRAR MANUAL address the NAT forwards it to the Internet and keeps an association between the private address and the port used for the forwarding In this way the association table can be set up There are hundreds of other ways to set up and maintain the NAT table The mechanism is often combined with a firewall that inspects packets during the forwarding process The Internet Protocol V6 solves the NAT problem in a different way They simply use m
47. o a value depending on the html port that you specify You can edit the file and modify the value The installation script will install a command rcsip proxy rcsip proxy start starts the proxy while rcsip proxy stop terminates the proxy process After the installation you should see that the proxy is running Open a web browser to see if the proxy is up and running Reboot the system and check whether the sip proxy was started automatically after the reboot You can then continue with the installation using the web browser Stop and restart the proxy with the rcsip proxy command to check whether the configuration has been saved After several installations the directory could look like this lrwxrwxrwx 1 root root 30 Aug 24 11 42 proxy gt snom sip proxy 1i386 linux 2 12 twes 1 root root 1472 Aug 22 16 17 proxy txt lrwxrwxrwx 1 root root 57 Aug 24 11 42 proxy manual pdf gt snom sip proxy i386 linux 2 12 snom 4S SIP Proxy 2 12 pdf drwxr xr x 2 root root 73728 Aug 24 11 56 registrations drwx x x 3 root root 4096 Aug 12 14 09 snom sip proxy i386 linux 2 1 bk Geet 1 root root 3902694 Aug 12 14 09 snom sip proxy i386 linux 2 11 tgz drwx x x 3 root root 4096 Aug 24 11 41 snom sip proxy i386 linux 2 12 1W 1 root root 3903533 Aug 24 10 32 snom sip proxy i386 linux 2 12 tgz snom technology AG e 25 snom 4S Proxy REGISTRAR MANUAL
48. ogy AG All rights reserved snom technology AG e 19 snom 4S Proxy REGISTRAR MANUAL At the beginning of the installation the setup program asks you to accept the license conditions see fig x 2 Please read them carefully then select the accept button and press next to accept the conditions If you decline the installation will be aborted After accepting the license agreement the next screen asks you to enter your personal information Enter your name and the name of organization You can then select the location where the proxy s files will be put The installation program proposes a reasonable location but if you want to you can change it After this the installation asks you for the location where the registration information will be put This directory needs write access and will contain the information for registered users The installation program proposes a location relative to the proxy installation directory but it might be useful to specify a different location for this e g Figure 4 2 Installation License Agreement E License Agreement sn om Please read the following license agreement carefully YoIP phones i snom 45 Proxy Registrar InstallShield Wizard Copyright 2002 snom technology Aktiengesellschaft Pascalstr 10e 10587 Berlin Germany Version 2 0 4ll rights reserved No warranty There is no warranty for the program to the extent permitted by applicable law Ex
49. on you can find out if the call is local international going to the boss and so on The matching process is done using the following wildcards matches any character as long as there is one matches a E164 number 0 9 and also and matches any character multiple times even if there is no character e Do matches E164 numbers multiple times even if there is no digit ou matches one of the hostnames of the proxy matches the PSTN gateway a z matches a character range in this example from a to zZ Static Routes Mode User Group Pattern Destination Use Gateway zl sip Ge sip user 192 168 0 248 506 Deny sw sip 4 sip 0192050 sip 1 9 0 sip 1 9 a Use Gateway sip 192 168 0 248 sip 0 192 158 0 22 Use Gateway el sip 11 0 sip user 192 168 0 248 506 The comparison process includes the sip identifier at the beginning of the URL The action can be one of the following Allow tells the proxy to use this number as is Deny tells the proxy to forbid this number error code 403 Forbidden e Incomplete tells the proxy to signal that more digits are expected e Use Gateway directs the call to the provided URL pattern typically a PSTN gateway e Not Found triggers the proxy to send a 404 Not Found error code A On e Configuration snom 4S Proxy REGISTRAR MANUAL The destination pattern may incl
50. oncepts snom 4S Proxy REGISTRAR MANUAL the destinations that are provided with the 3xx response and puts them on the list This is done using the probability of the underlying registrations and redirected contacts may have an even lower probability If the 3xx response for the only pending request the proxy passes the response through to the request client The client itself then takes care of the redirection This is important in cases where a call from a PSTN gateway comes in and should be redirected to a PSTN number The gateway then does not have to pass the call through the proxy it can immediately redirect the call on the PSTN level This does not work however if the call is redirected to more than one PSTN number in which case the call will have to go through VoIP In many environments users are registered with a high probability and the mailbox is registered as well but with a low value Even if the phone is switched off the proxy will redirect the call to the mailbox after a timeout Network Address Translation One of the biggest problems with the Internet version 4 is that it has a limited address range IP V4 defines 32 bits for addresses which were distributed according to a geographic scheme at a time when the success of the Internet protocol was hard to envision Regions like Europe or Asia in particular did not receive enough numbers to connect every network element with its own IP address Because of this in ma
51. ones are also called user agents and behave in a client server manner somebody being the user agent client UAC and somebody the user agent server UAS In SIP there is no conceptual difference between a hard phone and a soft phone The snom 100 VoIP phone or Microsoft Messenger are examples of this kind of system snom technology AG e 11 snom 4S Proxy REGISTRAR MANUAL Proxies Proxies forward requests and help the user agent carry out its tasks Stateless proxies just forward messages and serve as a hop on the path from a user agent client to a user agent server The rules for hopping may depend on all kinds of rules e g traversing NAT using a Stateless proxy Stateful proxies keep a list of pending requests This way proxies can forward requests to different destinations at the same time When the responses come back from the destinations the proxy merges the responses determines the best result and passes it down to the user agent that sent the request UAC The snom 4S proxy is a stateful proxy Location Server From RFC3261 we read A location service is used by a SIP redirect or proxy server to obtain information about a callee s possible location s It contains a list of bindings of address of record keys to zero Or more contact addresses The bindings can be created and removed in many ways this specification defines a REGISTER method that updates the bindings In other words the location ser
52. oth of them are down will the service go to www anycom de The probability of contacting sip server is 5 6 the probability of contacting 1 6 as the preference sum is 6 That means that most of the load goes to sip server 54 e Configuration Registering Phones As an example we show you here how to register a snom 100 VoIP phone and a Microsoft Messenger with the proxy Important Before you can try this on your proxy you need to set up the proxy snom 100 Registration We assume here that the proxy has the address 192 168 0 182 This address could of course also be a DNS name but in this example we want to use explicit IP addressing The phone is behind NAT and has a NAT gateway located at 192 168 0 1 Account 1 Name Account cst Registrar snornag de Mailbox All we need to do is fill in the Name the Account and the Registrar information Because we are behind NAT we also need to provide the outbound proxy see the information on NAT gateway Looking at the trace of the phone see next page we see the request going to the proxy and the response coming from the proxy snom technology AG e 55 snom 4S Proxy REGISTRAR MANUAL Microsoft Messenger Registration Microsoft Messenger supports SIP from Version 4 6 ongoing To register the messenger with a snom proxy you need to carry out the following steps e Open Microsoft Messenger Go to Extras Options e Inthe Tab Accounts select communication ser
53. ral SEES een ere GER 35 Selten ge AION ME 38 POURING aan ann a ebene hans anne aa nung 40 Domain Administration EE 43 User Administration ET 44 KIEREN 45 Error Information aa KEEN EEN ENNER n nun nun KEEN NN KEREN 49 Welcome Mess en nern 52 KiC 53 Registering Phones z nunnnunuununnnnnnnnunnnnnnnnnnnnnnnnn 55 snom 100 e Ee Le EE 55 Microsoft Messenger Registration sssssserssrerrrrrrrenrsrenrerrnrerrenre 56 Malntenance EE 59 Registered E RER 59 SUR e CEET 60 SIP Te 6 e EE 63 EOGAIN G KEE EE 65 More InforMmati i sera 67 DOIN ESS EE 67 Sa GON EE 67 Other useful information z22000nenennnonnnnnnnnnnnnnnnnnnnnnnnnnn ann nun 68 EE ee 68 6 e Contents The Voice over Internet Protocol Today there is a wide choice of different switched network products Telephones have now been being built for more than a century and their technology is well understood and proven Why choose a different technology Modern communication infrastructures transport much more than just one application email http files instant Messages videos music so it is only natural to include voice in the list of applications and use one infrastructure for all of them Voice is a real time application Sending voice over the Internet Protocol is called VoIP The delay between sending a packet to the network and receiving it needs to be minimal and constant and this makes specific demands on this application Most network equ
54. rmor com sipping drafts SIP standard used for this manual http www ietf org RFC 3261 Path extension for registering clients www softarmor com sipwg drafts draft snom technology AG e 67 snom 4S Proxy REGISTRAR MANUAL willis sip path 08 txt Other useful information General Information http iptel org Windows Messenger http www microsoft com WindowsxXP pro techinfo planning networking windowsmessenger asp snom home page http www snom de Footnotes This standard is now obsolete Many products currently on the market are compatible with this obsolete RFC You should be aware of this when buying SIP technology S Also known as user agents or terminals 3 TLS is not supported in the current version S According to the draft RFC3261 68 e More Information Symbole 404 484 Translation 42 A Architecture 11 Audio 11 Authentication 15 Automatic starting 24 B Bandwidth 7 C Call Logs 60 Call Log File 41 Call Parking 9 13 Call Picking 9 Call Pickup 11 Challenging 27 Codec preference 16 Conferencing 13 17 Configuration 11 33 Contact 59 D Delay 7 Delete 60 DHCP 11 Dial Plan 45 Dial plan 15 DiffSrv 7 DNS 11 52 DNS SRV 28 DSL 16 Index DTMF 13 E Echo Compensation 11 Email 7 Error Information 17 49 ETSI 8 Expires 60 E Failure recovery 15 Find Me 9 Firewall 16 Force authorization 37 G Gateway 9 Gateways 13 General Concepts 27 General Settings 34
55. ser bit_ secret HTTP password eteeee HTTP password SE confirm SIP Port The SIP port defines where the proxy expects SIP traffic Typically this will be port 5060 If you use a different port you should make sure that all clients use that port too This can be done by appending the port to the URL explicitly or by using DNS SRV see below Proxy realm When the proxy challenges users for authentication see above it needs a proxy realm to do so The clients search the list of possible user names and passwords according to this realm value If there is only proxy the default value should be set to snom but if packets might run over several proxies you should choose a more unique value like SIP proxy on 36 e Configuration snom 4S Proxy REGISTRAR MANUAL mycompany com Remember that these values need to be set up on the user agents that you plan to use with the proxy as well TCP threshold SIP uses both reliable and non reliable transport layers The snom proxy version 2 14 supports UDP and TCP transport layers When the proxy needs to send a request it has to make a decision which transport layer to use The TCP threshold value is compared against the packet length If it is less that the threshold value the proxy uses UDP otherwise TCP If you want the proxy to use only UDP you can enter a large number here e g 1000000 if you want the proxy to use only TCP enter a 1 here The recommended valu
56. sported within a reasonable time Usually there is acceptable quality but it may happen that calls suddenly break off that there is significant delay or that packet loss causes stuttering It is important that users know what to expect Cell phone users know that driving through a tunnel may break the call and Internet telephony users must be aware that talking for free may compromise call quality snom technology AG e 9 snom 4S Proxy REGISTRAR MANUAL 10 e About VoIP The SIP Architecture User Agents In a SIP network the phones make up most of the brain power unlike traditional telecoms equipment which can not scale so well they play and record audio they compress and uncompress the digital audio they do echo compensation they compensate for packet jitter and packet loss they look for the destination they retrieve their configuration information they keep track of phones that offer a call pickup they publish their state upon request they determine and publish the probability of finding somebody they terminate one or more identities they redirect calls when nobody picks up they are part of a virtual LAN they search address books LDAP they search internet addresses DNS A DNS SRV they usually include a web server they send an receive instant messaging information they publish network management information SNMP they behave like normal computers on the network DHCP DNS Ph
57. t This example is for Germany Mode User Group Pattern Destination 48 e Configuration snom 4S Proxy REGISTRAR MANUAL 4 sip 01 5 Use sip 4 sip 01 S sip user gw Gateway Use sip 101 sip 01 sip user gw Gateway Rules 1 3 redirects call to the gateway if at least three digits are available Rule 4 defines an exception to this rule if the number starts with 01 and has at least 11 digits like 01721234567 These numbers are denied for all users and rules 5 and 6 define the exception to this rule users 400 499 and user 101 is allowed to place these calls 3 3 Use sip sip user gw Gateway E 3 Error Information Should something go wrong a telephone system usually generates error reports In many cases the exact error messages are visible at the protocol level but the user does not get more than a busy tone SIP offers improved error information to users The error information may be on a web page e g http www company com error explanations err_404 htm but it may also be a SIP URL While most VoIP phones can not display http content they can place a call to an announcement server that reads out the error message This means that the system is much Smarter than traditional telephone systems You can even customize the announcements according to your special requirements snom technology AG e 49 snom 4S Proxy REGISTRAR MANUAL
58. trieves the DNS address from the registry while the Linux version reads out the respective etc file To be found you need the correct DNS server configuration If you only have one proxy running and you do not plan to use redundancy all you need to do is make your host known in this DNS server To use the DNS searching support you need to define entries for _sip _udp and _sip _tcp for your domain and assign weights and probabilities to the different hosts that serve these services A configuration file for Linux might look like this AA snom technology AG e 53 snom 4S Proxy REGISTRAR MANUAL STTL LD anycom de IN SOA fox anycom de hostmaster snom de 2002050111 serlal LD refresh 2H retry 1W expiry 1D minimum IN NS fox IN NS ns2 nameserverl21 com MX 10 mail anycom de _ Sip TCD anycom de IN SRV 0 5 5060 sip server anycom de IN SRV 0 1 5060 test anycom de IN SRV 1 5 5060 www anycom de Sip udp anycom de IN SRV 0 5 5060 sip server anycom de IN SRV 0 1 5060 test anycom de IN SRV 1 5 5060 www anycom de localhost IN A LZ Os OL S IN A 232 145 142 95 anycom de IN A 232 145 142 995 test IN A 232145 142495 WWW IN A 232 145 142 96 sip server IN A 232 145 142 97 In this example there are three choices for accessing the proxies for anycom de The first two sip server anycom de and test anycom de have the weight 0 and as long as one of them is up they will be contacted Only if b
59. ude some special variables user start ength The username of the destination If the start position is present a substring starting at position start is taken If the length parameter is present only length characters are copied host The host name of the destination port The port of the destination If no port is available the default port 5060 is used cport The port of the destination preceded wit a colon If no port is present this variable returns the empty string parm The parameter list of the destination head The headers of the destination url The complete destination url A typical destination pattern could be sip user 1 192 168 0 248 5060 In this example the first digit of the dialled number is removed and send to a PSTN gateway The proxy checks all rules of the dial plan This has the effect that the last matching rule will be executed not the first one Example 1 Setting up overlap dialling In this example the proxy should try to use the PSTN gateway when more than three digits have been dialled Otherwise the number Should be marked as incomplete Rule Mode User Group Pattern Destination ze fonsor T Rule 1 tells to use the PSTN gateway where at least four digits are available and the called proxy is the local proxy The star behind the tilde matches port numbers which might be part of the URL This can be left snom technology AG e 47 snom 4S Proxy RE
60. ver finds out where a request to a domain the proxy feels responsible for should go Registrars User agents register with a registrar When a request for the user agent arrives at the registrar it redirects the request to the location that was previously stored in the internal database The registrar is the part of the location server that can be controlled with REGISTER requests So snom 4S Proxy Location Server would be a better name for the product 12 e SIP Architecture snom 4S Proxy REGISTRAR MANUAL Media Server Strictly speaking the media server is just a special kind of user agent Typically it is able to deal with several calls at the same time and is a located on a PC or workstation The media server has the following tasks e Implement mailbox function When a user is absent the user agent of the stateful proxy redirects the call to the mailbox so that the caller may leave a message The owner of the mailbox calls the mailbox directly to listen to messages e Implement music on hold Using a fat client all kinds of music tastes can be played with highest possible quality e Implement call parking Calls can be parked on the media server until a user picks the call for processing In the meantime the caller can enjoy the music on hold using DTMF keys to select his favourites e Implement conferencing services Three or more persons dial into the conference server which mixes the audio streams for each parti
61. vices and enter the URL that you want to be registered with e g fred feuerstein sno mag de e If you need an outbound proxy you can enter this information when you click on Advanced Select UDP transport mechanism and set the Servername of IP address to the address of the outbound Figure 7 1 snom 100 Registration Messages Sent to udp 192 168 0 1 5060 at Wed 31 Dec 1969 21 25 22 458 GMT REGISTER sip snomag de SIP 2 0 Via SIP 2 0 UDP 192 168 0 11 5060 branch z9hG4bK 9jodhbwsul3y Max Forwards 70 From Theo Test lt sip test snomag de gt To Theo Test lt sip test snomag de gt Call ID 00004c4165c8 thzmqdslasz 192 163 0 11 User Agent snom100 1 11g CSeq 10 REGISTER Route lt sip 192 168 0 1 1r gt Contact lt sip test 192 168 0 11 5060 line 1 gt q 0 7 Expires 86400 Content Length 0 Received from 192 168 0 1 5060 at Wed 31 Dec 1969 21 25 22 614 GMT SIP 2 0 200 OK Via SIP 2 0 UDP 192 168 0 11 5060 branch z9hG4bK 9Jodhbwsul3y From Theo Test lt sip test snomag de gt To Theo Test lt sip test snomag de gt Call ID 00004c4165c8 7tbzmq d5lasz 192 168 0 11 Contact lt sip test 192 168 0 11 5060 line 1 gt CSeq 10 REGISTER Date Sun 9 Jun 2002 18 19 54 GMT Expires 3600 Content Length 0 56 e Registering Phones snom 4S Proxy REGISTRAR MANUAL proxy If you go to the trace page of the proxy you can see the registration messages Figure 7 2 Options for Microsoft
62. when there is nobody available to handle a call In these cases the media server helps out e Mailbox When nobody picks up a call the caller can leave a message on a mailbox The owner of the mailbox receives notification on his phones and an email with voice mail as an attachment e Music on hold When a call is put on hold the waiting party can listen to some music or announcements Calls can also be parked on a music on hold server e Conferencing services When more than two people want to talk in a telephone conference the media server can introduce new participants ask for pass codes and mix the audio streams in such a way that participants do not hear themselves e Error explanations When something goes wrong the media server explains what it was snom technology AG e 17 snom 4S Proxy REGISTRAR MANUAL 18 e snom 4S Framework Installation Windows Installation Important If you are doing an update you need to stop and uninstall the old proxy first see below After double clicking on the setup executable the installations program starts up see fig x 1 Press Next to begin the installation Figure 4 1 Installation Welcome Screen ite snom 45 Proxy Registrar InstallShield Wizard EN m F P Welcome to the InstallShield Wizard for snom 45 Proxy Registrar The InstallShield Ri Wizard will install snam 45 Proxy Registrar on your computer To continue click Next Copyright 0 2002 snom technol
63. y net The list may also contain addresses which can only be located via DNS SRV This is very helpful in situation when you want to run you mail www and sip server on different machines but they should Share the same name e g company com is the root domain but the sip server is running on sip company com You should also include the IP address of the proxy because many user agents need to register with the IP address of the proxy 34 e Configuration snom 4S Proxy REGISTRAR MANUAL Using the local host name like tango is normally not helpful as this hostname cannot be resolved by DNS If you do not plan to locate the SIP server via DNS you should just put in your IP address here License Key Enter the License Key into this field The key depends on the list of host names and the license type After pushing the save button the web client should show the license type and the menus for the license type become available If the web client shows not licensed please send the list oh hostnames and the IP addresses to mailto support snom de General Settings There are a number of general settings that you should set up in the beginning To do this go to the Administration Settings menu item snom technology AG e 35 snom 4S Proxy REGISTRAR MANUAL Proxy Settings General Behavior gt IP port S060 Proxy realm snomag de TCP threshold 1300 Log Level 7 Web server HTTP port oggi HTTF u
64. y with the web browser on the local host using the URL http r127 0 0 1 lt http ports so you don t have to search for it If you don t fill in any data or cancel the dialog port 80 will be used The SIP port defines where the SIP traffic is expected This will be port 5060 in most cases and you should change this port only if you know exactly how the proxy can be addressed with a different port number After finishing the setup wizard check that the proxy is running If you do not want to reboot your system because it is running other critical applications you can also manually start the service in the services section of the Windows control interface Check that the installation has been successful by checking the Services field of Windows Open the services Window and look for snom 4S SIP Proxy Registrar The status should be Started If this is not the Figure 4 5 Software Dialog in Windows ER Add Remove Programs z ioj x JI fm WW a Currently installed programs Sort by Name ii Ge snom 45 Proxy Registrar Size Change or Remove Programs Click here For support information Used To change this program or remove ik from your computer click Change or Remove ef 2 Add Mew Programs 4 Sound Blaster AUDIOPCI128 22 e Installation snom 4S Proxy REGISTRAR MANUAL case you should invoke the proxy by selecting start In this case we recommend rebooting the system to ma

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