[OpenSIPS-Users] Mediaproxy ver 2.3.4 - Conntrack meets Music on Hold

Stuart Marsden stuart at myphones.com
Thu Jul 2 11:05:59 CEST 2009


Hi,

It can be made to work - trust me

Phone A puts Phone B on hold

The new Session A-> MoH Invite contains the relay  port of the existing 
A->B call (functionality fixed by the phone, it thinks it is passing 
phone B)

the MoH server will now start to send audio to the mediaproxy session 
for the original A-B Call

you now replace phone A in that session with the IP:port of the inbound 
MoH RTP

audio will now flow from the MoH  to Phone B

when Phone A takes B off hold the original connections will be 
re-established

We have a well defined subnet were all our servers  live, so you can 
make this process secure by restricting this operation to that subnet

Stuart


Ruud Klaver wrote:
> Hi,
>
> On 30 Jun 2009, at 19:42, Stuart Marsden wrote:
>
>>
>> The problem is the Sipura/Linksys/Cisco  Phones do it the other way 
>> round - the phone going on hold  (A) sends a normal sendonly to the 
>> caller(B) . Then (A) sends a brand new invite to the MoH server(C) , 
>> passing what it thinks is the  SDP of the phone (B), but is actually 
>> the mediarelay
>>
>> The 200OK SDP from the MoH sever is not used
>>
>> So MoH starts to send Audio to what it thinks is (A) but actually 
>> sends it to (B)
>
> So the phone actually starts a completely new session to the MoH 
> server, which never receives any RTP in this session? This can never 
> work, because the relay needs to receive RTP from the other endpoint 
> of the session to know where to send the RTP from the MoH server to. 
> All it has learnt from the SDP exchange is its own IP, because that 
> was put as the RTP endpoint by phone A.
>
> Ruud Klaver
> AG Projects
>
>




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