[SIPForum-discussion] SIP INFO method and mid-session

Abinash Sarangi s_abinash at hotmail.com
Mon Oct 8 11:10:55 UTC 2012

Hi Kwanghee,

If the INFO would have been sent by the UA, it would have been reasonable. Lets discuss about a scenario, where the call is getting connected to a IVR server or VM server, and UA is getting some early media (183 session in progress) where the IVR or VM server wants it to dial a PIN so that the call will be subsequently connected to a final destination.
In this scenario, UA can send INFO(Out of band) to send the digits(DTMF). In your scenario, GW is sending INFO, not sure what they want to deliver. Is this GW your product or some vendor's.



From: theidea at lguplus.co.kr
To: discussion at sipforum.org
Date: Fri, 5 Oct 2012 10:00:44 +0900
Subject: [SIPForum-discussion] SIP INFO method and mid-session

Hi all,


I want to discuss about  SIP INFO method.

According to the rfc 2976, 

The INFO method
is used for communicating mid-session signaling

    information along the
signaling path for the call.


When is the mid-session point?  receiving
18x, 200 or sending ACK?


Is it reasonable the following call flow?







   183              <===



INFO              <===



In my opinion, Proxy will discard INFO method.
Because the mid-call is not established between UA and GW


How about you?




KwangHee Choi


Principle Research Engineer / Ph.D.

Communication Service Development Team


34, Gajeong-Dong, Yuseong-Gu, Daejeon,
Korea 305-350

e-mail   : theidea at lguplus.co.kr

tel        :

mobile   : +82-10-8080-8202

fax       :



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