[SIPForum-discussion] recvonly in sdp

[Kashif Husain]

>The port of non-zero is not required, but I would include it for
interoperability.

Correct. It is not mandated to have non zero port, but then the media
direction will become irrelevant when you make it zero. I think this was
the original query.

On Tue, Sep 11, 2012 at 11:29 PM, Stephen James <sjames_1958 at yahoo.com>wrote:

> The port of non-zero is not required, but I would include it for
> interoperability.
>
> From 3264 - this indicates that zero is allowed. But, you might run into
> problems with implementations that do not support it.
> Simply send the same port as in the previous SDP. Interesting, you have
> 0.0.0.0 for your IP address and are stating recvonly - which doesn't make a
> lot of sense.
> You are receive only to a IP of 0.0.0.0. Perhaps you intend sendonly, if
> you use that then you don't have to zero out your IP address, which is no
> longer recommended.
>
> A port number of zero in the offer indicates that the
>    stream is offered but MUST NOT be used.
>
>
>
> Stephen James
> sjames_1958 at yahoo.com
>
> We are not princes of the earth, we are the descendants of worms, and any
> nobility must be earned.
>
>
> ------------------------------
> *From:* Prem chandiran <toprem.m at gmail.com>
> *To:* discussion at sipforum.org
> *Sent:* Tue, September 11, 2012 11:06:09 AM
> *Subject:* [SIPForum-discussion] recvonly in sdp
>
> Hi all,
> for putting a caller in call hold we are sending the following sdp.
>
> v=0
> o=46727870367 1338208426 1338208966 IN IP4 10.47.16.5
> s=SCM
> c=IN IP4 0.0.0.0
> t=0 0
> m=audio 37384RTP/AVP 0
> a=ptime:20
> a=rtpmap:0 pcmu/8000
> a=recvonly
>
> my question is when we send a=recvonly at that time do we need to mention
> port in m attribute as mentioned in the above example or we have to give
> port as 0 in m attribute?. i checked rfc 4566 in section 5. SDP
> Specification i am able to find an example which is similar to the above
> sdp. but still i am raising this concern since i am unable to find any line
> in the rfc 4566 specifying while sending recvonly sdp must have m attribute
> port as 0 or any valid port number.  if any rfc is there plz mention the
> same . I kindly request you all to help in this.
>
> Thanks,
> Prem
>
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