Hello,
with liblinphone it is not possible to place a new call while there are incoming calls ringing. Fails with error 'linphone_core_invite_address_with_params(): sound is required for this call but another call is already locking the sound resource. Call attempt is rejected.'
however, the other way around, when a new call comes when I have active outgoing call, it is completely fine and it rings at the background.
The error says something about locked sound resource, which is questionable since it works the other way around plus since I have ringing turned off (not needed for callcenter operators, they have incoming calls all the time)
Before anyone asks why would anyone ever do that: callservice operators.
~David