Re: [Sip] Warning header

[isshed <[e-mail]>]

Thank for your response.

As you correctly said the warning code 306 indicates that the recipient
cannot understand one of the a= lines. But in this case recipient is
understanding the a=rtpmap:100 UNACCEPTABLECODEC/8000 line. Only thing it is
not understanding is the media format(i.e. encoding type). I think 306 is
best suited for the case of a new attribute i.e a=useless.
If you ask me i would still say that warning code 305 is best suited.

Thanks,
On Thu, Mar 10, 2011 at 9:13 PM, Worley, Dale R (Dale) <[e-mail]>wrote:

> ________________________________________
>  If an initial INVITE from an endpoint offer contains the sdp as follows.
>
> m=audio 15190 RTP/AVP 100 101\r\n
> a=fmtp:18 annexb=yes\r\n
> a=fmtp:101 0-15\r\n
> a=rtpmap:100 UNACCEPTABLECODEC/8000\r\n
> a=sendrecv
>
> the terminating endpoint returns an error response 488 with a warning
> header as follows.
>
> Warning: 306 132.177.120.67:5060 "Attribute not understood"
>
> Is 306 is correct response?
> ________________________________________
>
> The response is 488, which is correct if the recipient cannot find suitable
> codecs in the SDP offer.
> This makes sense, as the SDP contains no audio coded.
>
> The warning code 306 indicates that the recipient cannot understand one of
> the a= lines.  Unfortunately,
> the message does not indicate which a= line it does not understand.  My
> understanding is that
> if the interpreter of SDP does not understand an a= line, it should ignore
> it, which is aligned with
> the fact that the response contains a warning (as opposed to an error)
> about not understanding an a= line.
>
> I also see that the m= line mentions codec 101, but there is no
> a=rtpmap:101 line, which is I think technically
> an error, but in practice means that the recipient must ignore codec 101.
>
> Dale
>