I'm analyzing the effort of developing a VoIP app for Windows Phone.
Well, I can do almost everything without making my app a VoIP app but I can't use the audio routing to the earpiece unless I'm a VoIP app.
So, the VoIP API seems very nice and I've tried with Skype and Lync. These two Apps display the same Incoming call screen (with the answer and ignore buttons).
In my case, I need one more button on the incoming call screen. When receiving a regular GSM call I have a third button to answer with a SMS.
Any one knows if it's possible to customize the incoming call screen? I need to display three buttons