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SIP Stack with SIP Proxy - (VOIP)

, 11 Jun 2007 CPOL 686.7K 20.7K 156
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C# implementation of SIP
Screenshot - proxy.jpg

SIP Overview

SIP is an application-layer control protocol that can establish, modify, and terminate multimedia sessions (conferences) such as Internet telephony calls. SIP can also invite participants to already existing sessions, such as multicast conferences. Normally SIP uses UDP and TCP port 5060 and TCP 5061 for SSL communication. SIP protocol is very similar to HTTP, so if you have some knowledge about HTTP, then it is easy to learn SIP. SIP doesn't transfer session data like audio, video. RTP(real time protocol) is used for that, SIP just helps to open RTP streams.

SIP Message Example

INVITE sip:john@domain.com SIP/2.0
From: <sip:doe@domain.com>;tag=2084442460
To: <sip:john@1domain.com>
Via: SIP/2.0/UDP domain.com:5060;branch=z9hG4bK2df7b9194cd51e25
Call-ID: john@domain.com-4524j
CSeq: 1 INVITE
Contact: <sip:doe@domain.com:5060>
Content-Length: 226
Content-Type: application/sdp

<session description data, like RTP description>

SIP Server Types

stateless SIP server doesn't store any transaction info.
statefull SIP server creates and holds SIP commands transaction state.
registrar/location Allows users to register their locations and later to use that info to forward calls to registered contact.
B2BUA SIP server is like statefull + holds active calls state.(This is needed if call billing or full control of call is needed)
presence Provides user availability services, like if user is online,offline, ... .
... There are some more, but not so important ones.

Basic SIP Commands

  • INVITE - Initiates a session. This method includes information about the calling and called users and the type of media that is to be exchanged.
  • ACK - Sent by the client who sends the INVITE. ACK is sent to confirm that the session is established. Media can then be exchanged.
  • BYE - Terminates a session. This method can be sent by either user.
  • CANCEL - Terminates a pending request, such as an outstanding INVITE. After a session is established, a BYE method needs to be used to terminate the session.
  • OPTIONS - Queries the capabilities of the server or other devices. It can be used to check media capabilities before issuing an INVITE.
  • REGISTER - Used by a client to login and register its address with a SIP registrar server.

Ok, some ABC done, there are many documents on the internet, so it is not a good idea to rewrite these there.

If want more advanced information, then see:

SIP Proxy Demo Overview

This SIP proxy example just implements fully functional simple stateless, statefull, b2bua proxy. You can use hardware SIP phones or soft phones to play with this proxy.This is an advanced example, code is well commented, so beginners don't hate me because no more text here. Just read RFC 3216, see information links I noted earlier. After you go through those, if you then look at the code, it is all nicer then.

Some free available softphones are:

Version:
    11.06.2007
        *) Added B2BUA support.
    07.04.2007 
        *) Many bug fixes. 
        *) SIP -> PSTN and PSTN -> SIP gateway support. 
        *) Non-SIP URI gateway support. 

Contact Details

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Ivar Lumi
Estonia Estonia
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Comments and Discussions

 
QuestionHow to set enviroenment Pin
bliznak220-Jul-11 3:31
memberbliznak220-Jul-11 3:31 
AnswerRe: How to set enviroenment Pin
Ivar Lumi20-Jul-11 19:11
memberIvar Lumi20-Jul-11 19:11 
Generalvoip sip client with video Pin
waelsys200724-May-11 1:33
memberwaelsys200724-May-11 1:33 
GeneralRe: voip sip client with video Pin
Ivar Lumi24-May-11 2:41
memberIvar Lumi24-May-11 2:41 
GeneralA question about RTCP Pin
ywchen8-Apr-11 15:17
memberywchen8-Apr-11 15:17 
GeneralRe: A question about RTCP Pin
Ivar Lumi8-Apr-11 20:10
memberIvar Lumi8-Apr-11 20:10 
GeneralRe: A question about RTCP Pin
ywchen12-Apr-11 12:58
memberywchen12-Apr-11 12:58 
GeneralRe: A question about RTCP Pin
Ivar Lumi12-Apr-11 19:01
memberIvar Lumi12-Apr-11 19:01 
GeneralSIP_Authenticate AuthContext cannot get the password of the client application Pin
Sing52012-Mar-11 18:07
memberSing52012-Mar-11 18:07 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Ivar Lumi2-Mar-11 19:12
memberIvar Lumi2-Mar-11 19:12 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Sing52012-Mar-11 19:15
memberSing52012-Mar-11 19:15 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Ivar Lumi2-Mar-11 19:17
memberIvar Lumi2-Mar-11 19:17 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Sing52012-Mar-11 19:24
memberSing52012-Mar-11 19:24 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Ivar Lumi2-Mar-11 19:26
memberIvar Lumi2-Mar-11 19:26 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Sing52012-Mar-11 19:31
memberSing52012-Mar-11 19:31 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Ivar Lumi2-Mar-11 19:51
memberIvar Lumi2-Mar-11 19:51 
Demo app searches user/word auto matically: If user is created in demo apllication and realm of demo application and connecting client matches.
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Sing52012-Mar-11 20:05
memberSing52012-Mar-11 20:05 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application [modified] Pin
Sing52012-Mar-11 21:27
memberSing52012-Mar-11 21:27 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Sing52013-Mar-11 14:26
memberSing52013-Mar-11 14:26 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Sing52013-Mar-11 22:27
memberSing52013-Mar-11 22:27 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Ivar Lumi3-Mar-11 22:45
memberIvar Lumi3-Mar-11 22:45 
GeneralRe: SIP_Authenticate AuthContext cannot get the password of the client application Pin
Sing52014-Mar-11 3:00
memberSing52014-Mar-11 3:00 
Generalvoipcore Pin
abhisoft_abto21-Dec-10 0:21
memberabhisoft_abto21-Dec-10 0:21 
GeneralSIP Stack Pin
sdfsdfsdfsdfdfgdf30-Sep-10 2:55
membersdfsdfsdfsdfdfgdf30-Sep-10 2:55 
QuestionHow to fix error? Pin
Lý Tầm Hoan30-Jun-10 21:26
memberLý Tầm Hoan30-Jun-10 21:26 
Generalneed help for SIP to PSTN call Pin
ASGuru3-May-10 1:24
memberASGuru3-May-10 1:24 
GeneralRe: need help for SIP to PSTN call Pin
Ivar Lumi3-May-10 1:35
memberIvar Lumi3-May-10 1:35 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru4-May-10 0:31
memberASGuru4-May-10 0:31 
GeneralRe: need help for SIP to PSTN call Pin
Ivar Lumi4-May-10 0:36
memberIvar Lumi4-May-10 0:36 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru4-May-10 0:41
memberASGuru4-May-10 0:41 
GeneralRe: need help for SIP to PSTN call Pin
Ivar Lumi4-May-10 0:47
memberIvar Lumi4-May-10 0:47 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru4-May-10 1:00
memberASGuru4-May-10 1:00 
GeneralRe: need help for SIP to PSTN call Pin
Ivar Lumi4-May-10 1:35
memberIvar Lumi4-May-10 1:35 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru4-May-10 1:43
memberASGuru4-May-10 1:43 
GeneralRe: need help for SIP to PSTN call Pin
Ivar Lumi4-May-10 1:58
memberIvar Lumi4-May-10 1:58 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru4-May-10 18:57
memberASGuru4-May-10 18:57 
GeneralRe: need help for SIP to PSTN call Pin
Ivar Lumi4-May-10 20:02
memberIvar Lumi4-May-10 20:02 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru4-May-10 20:22
memberASGuru4-May-10 20:22 
GeneralRe: need help for SIP to PSTN call Pin
Ivar Lumi4-May-10 20:24
memberIvar Lumi4-May-10 20:24 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru4-May-10 20:28
memberASGuru4-May-10 20:28 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru7-May-10 23:51
memberASGuru7-May-10 23:51 
GeneralRe: need help for SIP to PSTN call Pin
Ivar Lumi8-May-10 0:10
memberIvar Lumi8-May-10 0:10 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru8-May-10 0:16
memberASGuru8-May-10 0:16 
GeneralRe: need help for SIP to PSTN call Pin
ASGuru10-May-10 20:35
memberASGuru10-May-10 20:35 
Questionhow much client we can connect? Pin
ASGuru23-Apr-10 21:12
memberASGuru23-Apr-10 21:12 
GeneralConfused about the basic settings Pin
filipcz19-Apr-10 6:16
memberfilipcz19-Apr-10 6:16 
Generalthe size of source code Pin
sntslm22-Mar-10 17:08
membersntslm22-Mar-10 17:08 
GeneralSample is not working properly.,. Pin
sajithkalady19-Mar-10 0:40
membersajithkalady19-Mar-10 0:40 
Generalthanks from PH Pin
mdingalla18-Oct-09 20:09
membermdingalla18-Oct-09 20:09 
GeneralGeneral comment Pin
mapick3-Oct-09 6:36
membermapick3-Oct-09 6:36 

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