Hello,
I'm testing Linphone when someone calls to my linphone user and we don't have compatible codecs. I can see that Linphone for Android returns a 415 error ("Unsupported media type") but never rings. So the transaction is invisible for the user.
I think it is problem because if the other end does not have implemented the 415 error it will try to continue calling my user and will keep my user busy. I have no possibility to reject the call inmediately sending for example a 603 response code.
Regards