Hi Paul,
Please see inline..
On 2/28/2015 10:58 PM, Paul Kyzivat wrote:
On 2/28/15 3:36 PM, brez wrote:
Hello,
Is it possible to establish a session (INVITE) with SDP constructed in
such a way so that neither party initiates a media session, nor
allocates resources (ports) for a non-existent media session?
In principle you can send an initial offer with SDP that has no m-lines.
AFAIK that is valid.
Thanks for giving me direction. This is indeed a valid case which is
described in RFC3264, Section 5, Paragraph 4:
The offer will contain zero or more media streams (each media stream
is described by an "m=" line and its associated attributes). Zero
media streams implies that the offerer wishes to communicate, but
that the streams for the session will be added at a later time
through a modified offer.
But I have recently had discussions with someone about this, and about
a UAS that wants to return 488 for this case. I *think* that in
*practice* you will find that many UASs will reject such an offer one
way or another.
Would that depend on the policy of service provider? i.e. you don't want
UAC who doesn't know how it wants to communicate, and by returning 488
you get rid of any such clients requesting your service.
Thanks,
Brez
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