I'm going to differ with Vivek to some extent. See inline below.
In any case, I suggest reading RFC6337.
On 10/19/15 2:21 AM, Talwar, Vivek (Nokia - IN/Noida) wrote:
Hi Sipuser,
Please find the responses as per scenario:
1. Its valid as terminating endpoint is mentioning its preferences although the
call will be established on codec2.
2. Yes its valid. Scenario can be of some early media announcement. Initially
call was established on codec 2 but some how call was say rejected and some
announcement is now being played from network and Media Server in picture will
use codec4.
3. Similar to 2.
4. Yes its possible to as far as stream used is same. It stream is new then new
m =line needs to be added.
5. Didn't get this question.
Thanks and Regards,
Vivek Talwar
-----Original Message-----
From: sip-implementors-boun...@lists.cs.columbia.edu
[mailto:sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of EXT K
sipuser
Sent: Monday, October 19, 2015 3:20 AM
To: Sip-implementors
Subject: [Sip-implementors] offer-questions.
Hi,I have few questions.
The questions are hard to read. I'm reformatting them.
1) INVITE with codec1,codec2,codec3200ok with codec2, codec3.
Is this ok to add codec3?
- INVITE with codec1,codec2,codec3
- 200ok with codec2, codec3.
- Is this ok to add codec3?
Yes it is. This means that either codec2 or codec3 may be used in the
session, or a combination of the two.
A common example of this is with g711 + telephone-events.
But it is allowed with any combination of codecs.
This is becoming more important because now there is active use form
multiple media streams within a single media session. These may use
different codecs. But a single stream can also switch codecs.
Some implementations can't handle this. In that case they should
negotiate down to a single codec, or a combination of codecs they can
use concurrently. (E.g. telephone-events and one other.)
2)INVITE with codec1,codec2,codec3183 received with codec2.Update Received with
codec4In early dialog state is this valid?
- INVITE with codec1,codec2,codec3
- 183 received with codec2.
- Update *Received* with codec4
- In early dialog state is this valid?
You don't say that that the 183 is reliable (100rel). If it was then
there would be a PRACK and 200 response to that.
The update is only valid if the 183 was reliable.
3)INVITE with codec1,codec2,codec3183 received with codec2.Update send with
codec4In early dialog state is this valid?
- INVITE with codec1,codec2,codec3
- 183 received with codec2.
- Update *send* with codec4
- In early dialog state is this valid?
How is this different from (2)? The only difference I see is *received*
vs. *sent*. But every message received must have been sent.
Is (2) assuming the update is opposite direction to invite, while in (3)
the update is in the *same* direction as the update?
In any case, my comments on (2) also apply to (3).
4)INVITE with codec1,codec2,codec3200 OK received with codec2.--call is
connectedUpdate Received with codec4
- INVITE with codec1,codec2,codec3
- 200 OK received with codec2.
- call is connected
- Update Received with codec4
Yes, this is fine. But the recipient of the update can reject it and
continue the call with codec2.
The sender of the update needs to be prepared to receive either codec2
or codec4 until the response to the update is received. He should keep
sending codec2 until he knows whether codec4 has been accepted.
5) if SDP offer has RR and RS=0.can answer be non-zero RR and RS?RR in offer
should be equal to RS in answer right?
I don't know what RR and RS mean in this context.
Can you please help in understanding these?
Good luck.
Thanks,
Paul
_______________________________________________
Sip-implementors mailing list
Sip-implementors@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
