A ramble about MSC, sip-connector and asterisk.

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Gullik Webjorn gullik.webjorn at corevalue.se
Sat Jan 12 12:48:24 UTC 2019


Hi,

Some weeks ago I managed to integrate osmobts with my asterisk server. 
In the beginning, I did

not get any call progress, ( as opposed to running WITHOUT asterisk ). I 
realized that defining

the msc to sipconnector socket effectively disabled all the logic 
related to this.

To remedy the situation, I set an asterisk "progress statement" whenever 
the extensions.conf

indicated a number belonging to my GSM network. This works OK, but now, 
I don't get call progress

on calls toward PSTN. These extensions do not have "progress" 
statements, since all SIP phones

interpret the call progress sip messages such as RINGING.


I am interested in your comments whether msc + sipconnector should 
emulate mobiles as "sip phones",

it does seem to just silently drop call progress messages, and is this 
the way it should work?

The functionality IS there, since when osmobts was bridging the calls, 
call progress WAS there.

Well, I kludged up a solution for the GSM-only situation, and this seems 
suboptimal.

I guess some clever asterisk hacking would solve that, possibly having a 
redundant progress statement

on ALL extensions would do it, but would I not lose "actual" call 
progress signals from the PSTN,

since asterisk would emulate them? Another way would be a small "local" 
asterisk.....before the *real* one.

Boldly moving on to MultiBTS and handover....

Gullik




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