Hi Pan,

If the Registered caller is a WebRTC client (Caller) whose preferred coded is 
VP8, calls a Phone (Called) whose preferred Video is H264, I should see


  *   INVITE from Caller to Kamailio (this is where the Caller is Registered) 
offering VP8
  *   Kamailio will relay the INVITE to Asterisk
  *   Asterisk will INVITE Called
  *   Called sends '200 OK' to Asterisk requesting H264
  *   Asterisk Sends '200 OK' back to Kamailio to be relayed to Caller 
accepting VP8

Is this correct?  Then I think one of the issues is that there is no fmtp line 
in the VP8.  The only codecs that have fmtp lines is for the H264 codecs.

Thank you,
-Steve

From: sr-users [mailto:sr-users-boun...@lists.kamailio.org] On Behalf Of Pan 
Christensen
Sent: Friday, June 8, 2018 11:06 AM
To: Kamailio (SER) - Users Mailing List <sr-users@lists.kamailio.org>
Subject: Re: [SR-Users] Peculiar Kamailio Asterisk behavior on outbound calls

That's not strange. The soft phone probably doesn't advertise support for VP8, 
so it's not chosen.
Calling from WebRTC, I assume that VP8 is the preferred codec and Asterisk 
accepts it. Asterisk then finds out that the soft phone doesn't support VP8 and 
negotiates a different codec with that client.

If you show us the SDPs of INVITE and 183/200 on both sides of Asterisk (in the 
order they are sent), we can tell you exactly what happens. Failing that, I'd 
say that the culprit is Asterisk, which probably negotiates two different 
codecs without the ability to transcode.

With kind regards
Pan B. Christensen
Developer
Phonect AS
From: sr-users 
<sr-users-boun...@lists.kamailio.org<mailto:sr-users-boun...@lists.kamailio.org>>
 On Behalf Of Wilkins, Steve
Sent: fredag 8. juni 2018 15:09
To: Kamailio (SER) - Users Mailing List 
<sr-users@lists.kamailio.org<mailto:sr-users@lists.kamailio.org>>
Subject: Re: [SR-Users] Peculiar Kamailio Asterisk behavior on outbound calls

Yes, for example a WebRTC Client (VP8) calls a Soft-Phone (H264).  What is 
strange is that if it is the other way around and the Soft-Phone calls the 
WebRTC client, it works.

Thank you

From: sr-users [mailto:sr-users-boun...@lists.kamailio.org] On Behalf Of Pan 
Christensen
Sent: Friday, June 8, 2018 9:00 AM
To: Kamailio (SER) - Users Mailing List 
<sr-users@lists.kamailio.org<mailto:sr-users@lists.kamailio.org>>
Subject: Re: [SR-Users] Peculiar Kamailio Asterisk behavior on outbound calls

Hello Steve.

Does Asterisk negotiate different codecs with each client? If so, it needs to 
transcode, which I believe is currently not supported for video. What does 
Asterisk send back to device A?

With kind regards
Pan B. Christensen
Developer
Phonect AS

From: sr-users 
<sr-users-boun...@lists.kamailio.org<mailto:sr-users-boun...@lists.kamailio.org>>
 On Behalf Of Wilkins, Steve
Sent: fredag 8. juni 2018 14:03
To: Kamailio (SER) - Users Mailing List 
<sr-users@lists.kamailio.org<mailto:sr-users@lists.kamailio.org>>
Subject: [SR-Users] Peculiar Kamailio Asterisk behavior on outbound calls

Hi All,

Issue: when a Call is made through Kamailio and Asterisk.  Asterisk uses 
incorrect Video RTP Payload Type when sending Video packets.

I have a situation where I make a call from Device A to Device B and Device A 
is Registered in Kamailio.  When Device A Calls Device B, Kamailio sends an 
'INVITE' to Asterisk, Asterisk then  'INVITES' Device B.  I get two-way Audio, 
the call stays connected, however, when Video packets are sent to Device B, the 
RTP Payload Type is incorrect.  The port is correct, but just not the Payload 
Type.

Here is where I think Kamailio is involved. In the first Invite from Kamailio 
to Asterisk, one of the offered Video codecs is '100 H264'; interesting enough, 
Device B wants to use '115 H264' and when Asterisk sends out Video packets, it 
is using '100' instead of '115', and of course I have no Video.  I don't know 
if this is just a coincidence but it sure seems like that is where the issue 
may lie.

Has anyone ever seen this behavior?  The Asterisk teams does not think it's an 
Asterisk issue.

Thank you,
-Steve
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