asterisk users - Jun 2007 - 180 Ringing with SDP

We're dialing a disconnected number via Level 3's vector network, and
are receiving this. The response has SDP in it. Apparently, Level 3 is
playing early media. Asterisk doesn't seem to know what to do with SDP
in a 180 RINGING, and just plays ringing. What am I missing here? How
can Asterisk see there's SDP, early media, in the response and act
accordingly?

 

SIP/2.0 180 Ringing.

Via: SIP/2.0/UDP xxx.yyy.34.195:5060;branch=z9hG4bK591743a1;rport=5060.

From: "Test Phone 2" <sip:+19256002182 at
xxx.yyy.34.195>;tag=as7e76044e.

To: <sip:+12059512018 at 4.55.16.99>;tag=gK0cc2d5ab.

Call-ID: 4d1db18c7d86e9e733f9f8b64c28c020 at xxx.yyy.34.195.

CSeq: 102 INVITE.

Contact: <sip:+12059512018 at 4.55.16.99:5060>.

Allow: INVITE,ACK,CANCEL,BYE,PRACK,UPDATE,OPTIONS.

Content-Length:  231.

Content-Disposition: session; handling=required.

Content-Type: application/sdp.

.

v=0.

o=Sonus_UAC 22562 17424 IN IP4 4.55.16.99.

s=SIP Media Capabilities.

c=IN IP4 4.55.16.66.

t=0 0.

m=audio 6288 RTP/AVP 0 101.

a=rtpmap:0 PCMU/8000.

a=rtpmap:101 telephone-event/8000.

a=fmtp:101 0-15.

a=sendrecv.

a=maxptime:20.

 

Doug.

 

 

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On 6/18/07, Douglas Garstang <DGarstang at interainc.com>
wrote:
> We're dialing a disconnected number via Level 3's vector network,
and are
> receiving this. The response has SDP in it. Apparently, Level 3 is playing
> early media. Asterisk doesn't seem to know what to do with SDP in a 180
> RINGING, and just plays ringing. What am I missing here? How can Asterisk
> see there's SDP, early media, in the response and act accordingly?
I could be totally off base here, but it's my understanding that a 180
is telling Asterisk to generate ringing on it's side, and that a 183
(with SDP) would tell Asterisk that the call is progressing and that
it should play the early media specified in the SDP.  I'm sure someone
there's probably someone on the list who is more intimate with the
details of SIP that can enlighten us further on the subtle differences
between the 180 and 183 provisional responses.

-Jared