[SIPForum-discussion] SIP Testing (INVITE without SDP)

[Chong Fah Sam]

Hi, 

 

This is because the inbound call is using the slow start (INVITE without
SDP). And also your softswitch is not supporting the delay offer (INVITE
without SDP).

The solution is either you can configure your softswitch to support the slow
start or request the incoming call enable the fast start.

 

Best Regards,

Sam 

  _____  

From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Shakil, Rashid
Sent: Thursday, March 13, 2008 10:18 PM (TT) 
To: discussion at sipforum.org
Subject: [SIPForum-discussion] SIP Testing (INVITE without SDP)

 

Hello All,

 

I am having call failure issues when my softswitch sending a SIP INVITE
without SDP for a redirect call (Inbound call from SIP redirected back to an
offnet number). The call scenario is as follows

 

1.	An Inbound call (PSTN to IP) comes in from SIP carrier. The user on
SIP side (our customer) enable the Find me feature to redirect the inbound
to an offnet number
2.	An outbound call goes out from my softswitch to the SIP carrier. The
INVITE for that outbound call has diversion header but no SDP
3.	In response to the outbound INVITE (without SDP) the upstream
Gateway sent me 480 Temporary Unavailable with this explanation "After
receiving the PSTN call, the gateway sends out the first INVITE. It receives
back the forwarded INVITE (with diversion header), but the INVITE does not
have any media specified. So the gateway then sends out a new INVITE to the
destination number, but sets media a=sendonly. The call is being rejected
because on the egress side, the INVITE goes out with a=sendonly (because
there was no SDP on the Ingress INVITE), but the 200 OK comes back with no
"a" setting, which means a=sendrecv".

 

I believe we can redirect a call with diversion header and without SDP. Is
this explanation from my upstream provider is correct do I have to send an
SDP for the redirected call. Please reply me so that I can move forward with
this issue. 

 

Regards,

 

Rashid Shakil.

 

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