[OpenSIPS-Users] [NEW FUNCTIONALITY] minor branch in TM parallel forking - media injection

Bogdan-Andrei Iancu bogdan at voice-system.ro
Sat Oct 11 19:04:19 CEST 2008

Hi everybody,

I made a small TM enhancement to allow injecting media into a call 
before establishing it. The idea is to fork a parallel branch to a media 
server that will use 183 Early Media to inject media into the call - it 
is mandatory for the media server to never accept (200 OK) the branch, 
but to keep it in early/provisional state.

When one of the real branches will be accepted, the 200 OK will override 
the 183 Ealy Media and proceed as a normal call.

The idea with a minor branch is to have a branch OpenSIPS will not wait 
to complete during parallel forking. So, if the rest of the branches are 
negatively replied OpenSIPS will not wait for a final answer from the 
minor branch, but it will simply cancel it. So, the branch to the media 
server will never affect the real forking/branching of the call - it 
will be simply transparent.

See more here : 

A nice applicability is to implement Ring Back Tones without any 
Application Agent/Server or B2BUA.


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