Is there any way (maybe by using mobilesubstrate) to "change" how the iphone dials a number? What I am trying to do is to have the iPhone to dial a number using my Google Voice account instead of my real number, but it's a pain to open GV Mobile every time to do that.

I've tried to make a symbolic link of the phone.app to gv mobile, and it actually opened the gv mobile app up, but it crashed right after.