I was able to use the root browser app to modify the permissions on my wife's phone and enable the native SIP feature ("internet calling") on my wife's android running gingerbread 2.3.6. I'm able to successfully register the softphone and outbound calls work perfectly, but when inbound calls are answered I can't hear the other party and the other party can't hear me. Then I disabled the native softphone and tried using the cSIPsimple app instead, but I end up with the same results. I've tried various configurations in cSIPsimple including the use of the ICE and STUN settings, but I have had no joy with inbound calls.

Strange thing is that I have configured my iOS device with a softphone application and both inbound and outbound calls work perfectly on it, so it can't be an issue with my home network, right?