[Freeswitch-dev] Implementing preferred channel selection in freetdm using sangoma isdn ?

[Matteo]

Hi,

the following applies to ftmod_sangoma_isdn.

Scenario:
some pri isdn switches does not like exclusive channel selection,
but needs the setup message to carry a preferred channel selection ie.

Adding this in freetdm (in setup message) and making it configurable
is easy and an example patch is attached.

BUT!

If the remote switch changes the channel, we need to "move" the current
freetdm channel to the one specified in the provisional response or setup ack.

According to q.931 is wrong to allocate a b channel before having
confirmed the right one to use, but right now freetdm allocates it immediately.
(maybe is worth changing that?)

So, I'm trying to understand all the stuff between freetdm and ftmod_sangoma_isdn
in order to modify it and make the preferred b channel selection working.

Any hint ? Which is the best way to "swap" a freetdm channel or move to another?
Is something the stack already allows or needs some major modifications?

mat
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