A newbe find. I just deduced that call progress is PLMN based when using
osmo-msc with an external nmcc,
such as asterisk. Thus, the solution to the problem "no call progress
tones", is to modify the asterisk extensions
with a progress statement. Since msc treats mobiles just as a number of
sip clients, all calls, including
mobile - mobile are directed via the external nmcc, and in this case it
is asterisks responsibility to
generate "call progress".
I modified
exten => _07575760XX,1,Dial(SIP/GSM/${EXTEN})
to
exten => _07575760XX,1,Progress()
exten => _07575760XX,2,Dial(SIP/GSM/${EXTEN})
this did the trick....the insight gets deeper....
Gullik