[Freeswitch-users] Questions on ISDN support for Freeswitch

[Albano Daniele Salvatore - Lavoro]

Hi to all,

shortly i'll make a pbx for a customer that uses a couple of isdn bri 
lines and, looking for hardware, i've seen that not too much expensive 
isdn cards that works well are the ones that uses hfc-4/8s controller 
(specifically i'll use a OpenVox B200P that has 2 ISDN ports and use an 
HFC-4S controller).

I've seen that FreeSwitch doesn't support mISDN but uses openzap (trough 
ozmod_isdn.so). I got some serious troubles using OpenZAP on analogical 
lines (bad dtmf recognition on fxs ports (like press 4 and get 44), 
annoying noise, busy/hangup tone unrecognized [tones, in italy, differs 
by cadency and not frequency], and more). Using tone_detect i bypassed 
the tone recognition problem and the noise was however acceptable: the 
blocking problem was the bad dtmf recognition. In the end (hope god 
forgive me) i put asterisk as (*1*)(*2*)sip proxy between zaptel and 
freeswich: i need to fix in config hangup cause detection but it seems 
to works fine.

So my questions are:
- Do freeswitch supports mISDN?
- If it doesn't support mISDN, tone and dtmf recognition will be done by 
the isdn card, the kernel module or will be done by openzap?
- There are alternative ways to use (*3*) mISDN with freeswitch, apart 
put asterisk as proxy?


Thank for your support!

Best Regards,
Daniele

---

(*1*) At beginning i tried using IAX but freeswitch segfaults when it 
try to answer the call and when i reload the module (trought reload 
mod_iax) shutdown routing didn't get called(the used iax library, 
smartly, start using another port without saying anything), however i 
need to do more testing: hope to open some tickets on jira in short.

(*2*) I've seen that mod_iax config file support a "context" variable, 
but it isn't used so i wrote a small fix to use it if context isn't 
specified in the iax request

(*3*) I need to use mISDN, rather other things, because i should use 
octasis soft echo cancellation and them supports only mISDN and Zaptel 
modules
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