Subject: [Sip] TCP to UDP rtcp media attributes in SDP not passing through SBC

From: Nitin Kapoor <[email-masked]>
Date: Fri, 12 Feb 2010 08:14:29 -0500

Dear Friend,

I have some query about UDP & TCP for signaling.

Basically I am using TCP protocol for signaling from my customer to SBC and
then SBC to Vendor using UDP for signaling. I mean CS user TCP to SBC, UDP
to carrier.  And OCS sends initial 183 with sdp that contains rtcp media
attribute information and SBC does not forward formation to carrier via UDP.

Call Flow is like this.

UAC (Private)                    SBC
     UAS(Public)

|-----------Invite(TCP)---------->
|                                                       |
|
|                                                       |
|<-------- 100 Trying ------------ |
                                          |
|                                        | ----------- Invite
(UDP)----------------------->|
|
|                                                       |
|                                        |<--------- 100 Trying
---------------------------|
|
|                                                       |
                                         | <---- 183 SDP Session
Progress-------|
|                                        |(183 SDP with RTCP Media
    |
|                                        |Attribute).
                                       |
|<--------- 183 SDP -------------
|
|
| 183 SDP Session
progress|                                                       |
| Without RTCP Media         |
                                               |
|Attribute
|                                                       |
|
|                                                       |
|
|                                                       |
|
|                                                       |

Could anyone please help me out on this scenario. Why it’s not sending the
RTCP attribute to my UAC? Is there anything related to standard.

I can share the Traces, if its required.

Thanks,
Nitin Kapoor