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

[Varadhan M]

KwangHee Choi,

You are correct, SIP INFO method can't be used before the INVITE's 200 OK

183 200 Ok allows you to transmit the media, so it should be possible to
transmit the RFC2833 or Inband DTMF

I found this as an limitation of SIP, since the scenario is common while
building Gateway device with SIP compatible and can't rely on SIP INFO
method.

Regards,
Varadhan M

On Fri, Oct 5, 2012 at 6:30 AM, KwangHee Choi <theidea at lguplus.co.kr> wrote:

>  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?****
>
> ** **
>
> UA------------Proxy-------------GW****
>
>    INVITE****
>
>    ===>           INVITE****
>
>                      ===>****
>
>                      183****
>
>    183              <===****
>
>   <===****
>
>                      INFO****
>
> 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****
>
> LG U+****
>
> 34, Gajeong-Dong, Yuseong-Gu, Daejeon, Korea 305-350****
>
> e-mail   : theidea at lguplus.co.kr****
>
> tel        : +82-42-712-4206****
>
> mobile   : +82-10-8080-8202****
>
> fax       : +82-50-5889-4206****
>
> =====================================================****
>
> ** **
>
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