Agree with Attila. So in the given circumstance the UAS could have 
responded to the invite with a 488 to indicate that it didn't support 
the offered media.

Another possibility is for the UAS to return an answer where the port in 
the m-line is zero, thus rejecting the media stream since it can't 
handle any of the offered media. It could also include in that m-line 
the codecs it *does* support as an indication, though they will not be 
used at that time.

Then the UAS could initiate another offer with the codecs it does 
support, in hopes of getting a working call.

Whether that is better than the 488 is arguable. Probably not in most cases.

        Thanks,
        Paul

Attila Sipos wrote:
> 415 is often confused with 488.
> 
> "415 Unsupported Media Type" is what you would use if if didn't understand
> the SIP message body content.
> 
> 488 (which is similar to 606) would be a more suitable response:
> 
> 21.4.26 488 Not Acceptable Here
> 
>    The response has the same meaning as 606 (Not Acceptable), but only
>    applies to the specific resource addressed by the Request-URI and the
>    request may succeed elsewhere.
> 
> and 606 is described as...
> 
>    The user's agent was contacted successfully but some aspects of the
>    session description such as the requested media, bandwidth, or
>    addressing style were not acceptable.
> 
>    A 606 (Not Acceptable) response means that the user wishes to
>    communicate, but cannot adequately support the session described.
>    The 606 (Not Acceptable) response MAY contain a list of reasons in a
>    Warning header field describing why the session described cannot be
>    supported.  Warning reason codes are listed in Section 20.43.
> 
> 
> Regards,
> Attila
> 
> 
> -----Original Message-----
> From: sip-implementors-boun...@lists.cs.columbia.edu 
> [mailto:sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of Peter 
> Nijhuis
> Sent: 27 April 2009 14:30
> To: Shanbhag, Somesh (NSN - IN/Bangalore); ext friend friend; sip fourm
> Subject: Re: [Sip-implementors] Query for SDP Negotiation
> 
> I think Callee should respond with 415 unsupported media type, since it is 
> not supporting media types 102, 0, 8 or 106.
> 
> Met vriendelijke groet, with kind regards, mit freundlichen Gruß
>     
> Peter Nijhuis
> 
> 
>   
>> -----Original Message-----
>> From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip- 
>> implementors-boun...@lists.cs.columbia.edu] On Behalf Of Shanbhag, 
>> Somesh (NSN - IN/Bangalore)
>> Sent: maandag 27 april 2009 15:07
>> To: ext friend friend; sip fourm
>> Subject: Re: [Sip-implementors] Query for SDP Negotiation
>>
>> The basic thing is CALLEE has to take the subset of codecs offered by 
>> CALLER and reply back.
>> But in your case, CALLEE is replying with different set of codecs (97
>> 101) in reply to CALLER codecs  ( 102 0 8 106 ) IMHO, since the 
>> capabilities mis-match, immdiately end the call using BYE / CANCEL 
>> which ever is relevant.
>>
>>
>> Somesh
>>
>> -----Original Message-----
>> From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip- 
>> implementors-boun...@lists.cs.columbia.edu] On Behalf Of ext friend 
>> friend
>> Sent: Monday, April 27, 2009 2:59 PM
>> To: sip fourm
>> Subject: [Sip-implementors] Query for SDP Negotiation
>>
>> Dear Folks,
>>        I have doubt in the following scenario.
>>
>> Caller's sdp :
>>
>> v=0
>> o=- 1234 1 IN IP4 10.10.20.35
>> s=-
>> c=IN IP4 10.10.20.35
>> t=0 0
>> m=audio 12000 RTP/AVP 102 0 8 106
>> a=rtpmap:102 iLBC/8000
>> a=rtpmap:0 PCMU/8000
>> a=rtpmap:8 PCMA/8000
>> a=rtpmap:106 telephone-event/8000
>>
>>
>> Callee's negotiated sdp :
>>
>> v=0
>> o=- 3449811996 3449811996 IN IP4 10.10.20.4 s=SJphone c=IN IP4 
>> 10.10.20.4 t=0 0 m=audio 49164 RTP/AVP 97 101 c=IN IP4 10.10.20.4
>> a=rtpmap:97 iLBC/8000
>> a=rtpmap:101 telephone-event/8000
>> a=fmtp:101 0-16
>> a=setup:active
>> a=sendrecv
>>
>> In this case,Is callee's negotiation method is wrong?
>>
>> Callee should send like m=audio 49164 RTP/AVP 102 106 rite?
>>
>> In this case, after call establishment,
>>              from caller sending RTP using 102 (UnKnown)
>>              from callee sending RTP using 97 (iLBC)
>>
>> So caller hearing callee's audio but callee not able to hear caller's 
>> audio.
>>
>> please clarify this issue.
>>
>> Thanks & Regards,
>> vijay
>>
>>
>>       Bring your gang together. Do your thing. Find your favourite 
>> Yahoo! group at http://in.promos.yahoo.com/groups/
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