[asterisk-ha-clustering] Asterisk clustering and transferring calls

[Brent Thomson]

I've got OpenSER as a proxy doing load balancing in front of several
Asterisk boxes. Each INVITE from any phone could theoretically land on
any of the PBXes. This means that if a phone is on a call and attempts
to transfer that call, the new leg (recipient of the transferred
original call) could wind up on a different PBX than the original call.
Asterisk gets *really* confused if it gets a REFER to a new call that it
doesn't know about. The end result is that transferring doesn't work
except in the rare event that the transferring phone's second call
happens to land on the same PBX as the first.

I can see a few different possibilities:

    - force all calls from the same SIP user through the same PBX
(undesirable from a load balancing and failover standpoint)
    - intercept the refer at the proxy, send some kind of command that
creates a channel between the two PBXes involved, then send a refer to each
    - similar to the last one, but detect the REFER at the proxy and do
a re-invite to one PBX and a refer to the other

Has anybody dealt with this before? Any ideas?

-Brent