[asterisk-users] Codec Negotiation problem

[Matthew Jordan]

On Thu, Jun 13, 2013 at 12:04 PM, <research at businesstz.com> wrote:

> Hi there
>
> I have asterisk 10.11.1 which seems to have problem negotiating codec.
>
> Scenario: SIP PHONE1 (XLite) extension 1003, allowed codecs alaw, h263p
> and SIP phone2 (Grandstream GXV3175) extension 1004, allowed codec alaw,
> h263p. I have tried similar combination of codecs and SIP phone but when
> making a video call, it report "Peer doesn't provide video". It seems
> Asterisk is failing to set capability correct. Both codecs are enabled on
> the SIP Phones
>
>
<snip>

The 200 OK response from the called XLite phone is declining the video
stream:

<--- SIP read from UDP:10.10.10.129:48464 --->
SIP/2.0 200 OK
Via: SIP/2.0/UDP 10.10.10.105:5060;branch=z9hG4bK368135b0;rport=5060
Contact: <sip:1003 at 10.10.10.129:48464>
To: "SAM"<sip:1003 at 10.10.10.105>;tag=0c90cc0c
From: <sip:1004 at 10.10.10.105>;tag=as24914503
Call-ID: MmNjOTczNDU5YjZmYjAyNWMxY2Q1MDZjODdhYzQwZjA
CSeq: 102 INVITE
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
SUBSCRIBE, INFO
Content-Type: application/sdp
Supported: replaces, eventlist
User-Agent: X-Lite release 4.5.2 stamp 70142
Content-Length: 234

v=0
o=- 13015615910543193 2 IN IP4 10.10.10.129
s=X-Lite 4 release 4.5.2 stamp 70142
c=IN IP4 10.10.10.129
t=0 0
m=audio 53188 RTP/AVP 8 101
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=sendrecv
m=video 0 RTP/AVP 115
<------------->
--- (12 headers 10 lines) ---
Found RTP audio format 8
Found RTP audio format 101
Found audio description format telephone-event for ID 101
Capabilities: us - (alaw|h263p), peer -
audio=(alaw)/video=(nothing)/text=(nothing), combined - (alaw)

Note that the port for the video stream is set to 0.

Asterisk is doing the correct thing: it notes that the answer to its offer
declined the video stream, so it disables video for the call between the
two endpoints.

Matt

-- 
Matthew Jordan
Digium, Inc. | Engineering Manager
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: http://digium.com & http://asterisk.org
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