[Freeswitch-dev] Implementing preferred channel selection in freetdm using sangoma isdn ?
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
It's not setup to do that right now, as you found. I'm not sure how invasive the changes may be to do this. On Jul 15, 2014, at 3:26 AM, Matteo <mbrancaleoni@voismart.it> wrote:
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<pri_exclusive.diff>_________________________________________________________________________
Hi Matteo, On Tue, Jul 15, 2014 at 3:26 AM, Matteo <mbrancaleoni@voismart.it> wrote:
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?)
You definitely want to read doc/ftdm-open-issues.txt in the freetdm/ directory for more information. This has been a known long-standing issue, and at some point I even started work in a branch, but did not follow up (not sure if the branch was ever pushed) and my employer lost interest in completing the work as none of our customers were requiring it and we moved on to work on more pressing needs. There might be a way to hack it in without heavy changes, but the right way to do it is significantly disruptive. It might be worth doing it, though, I have not heard much complaints from users, perhaps there is not that many people using FreeSWITCH for PRI. - Moy
participants (3)
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Matteo
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Michael Jerris
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Moises Silva