Alex Balashov wrote:
The B2BUA+SST approach seems clean, efficient, and at least from a theoretical point of view, rather reliable.
clean? I am not so sure any more, trying to hack something together to see where this gets. Is there a clean and simple method to do re-invite from the b2bua, which catches all the possibilities (changed session etc)?

e.g., one possibility, reinvite with last SDP from the other side

A                  b2b                  B
|---INVITE / SDPa-->|                   |
|                   |---INVITE / SDPa-->|
|                   |                   |
|                   |<-- OK/SDPb--------|
|                   |--- ACK ---------->|
|<-- OK/SDPb--------|                   |
|--- ACK ---------->|                   |
|                   |                   |
         ... sst timer expires ...
|                   |                   |
|<--INVITE / SDPb---|                   |
|                   |                   |
|--- OK/SDPc------->|                   |
       now what? ignore that, or do

|                   |---INVITE / SDPc-->|
|                   |<-- OK/SDPd--------|
     one more round of ping-pong?

|                   |                   |

or, other possibility, empty reinvite:
A                  b2b                  B
|---INVITE / SDPa-->|                   |
|                   |---INVITE / SDPa-->|
|                   |                   |
|                   |<-- OK/SDPb--------|
|                   |--- ACK ---------->|
|<-- OK/SDPb--------|                   |
|--- ACK ---------->|                   |
|                   |                   |
         ... sst timer expires ...
|                   |                   |
|<--INVITE          |                   |
|                   |                   |
|--- OK/SDPc------->|                   |
       now what? ignore that, or do

|                   |---INVITE / SDPc-->|
|                   |<-- OK/SDPd--------|
         one more ping-pong?

|                   |                   |

Maybe I just got confused and there is a simple solution?

Stefan

--
Stefan Sayer
VoIP Services Consulting and Development

Warschauer Str. 24
10243 Berlin

tel:+491621366449
sip:sa...@iptel.org
email/xmpp:stefan.sa...@gmail.com



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