On 9/17/2010 7:45 AM, anand madhab wrote:
> Hi, If m line is missing in invite request and 180, 200 response then what
> will be senario ?
> I dont understand the case, I mean i want to make a call with initially
> putting a person in hold ? please explain
> does caller need to reject the call
Your question isn't entirely clear. Can you show call flow?
I am guessing that the INVITE has SDP with one m-line, and the response
has SDP with no m-line ???
If so, I would expect the caller to send BYE and drop the call. The
answer SDP must have the same number of m-lines as the offer.
We don't usually specify behavior for non-conforming cases (which this
is), so the caller isn't *required* to send a BYE. But behavior after
that is undefined.
Are you implementing the UAS, and wanting to prevent media from flowing
immediately as the call is established?
You can do a number of things, depending on exactly what you want to happen:
- you can respond with an answer with matching m-line, with real address
and port, and include an a=sendonly or a=inactive to prevent media from
flowing to you. You have indicated that you are willing to use this
media, but not yet. In case of RTP-based media, *RTCP* will still flow.
- you can respond with an answer with matching m-line, and a non-zero
port, but with an address (c=) of 0.0.0.0. This is similar to prior,
except nothing will flow to you.
- you can respond with an answer with matching m-line, with a zero port.
This says you are rejecting the use of this media, but haven't rejected
the call. This is valid in principle, but its likely to upset some UAs,
because they don't know what they are supposed to do.
Paul
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