I live in China where it's cheaper to make national or international calls using 5 digit IP codes before the phone #, but it can be frustrating as I have to keep 2 numbers for my friends in different cities. The 1st # is the actual phone # which I use for SMS, and the 2nd is the phone # with preceding IP code which I call. Is there any kind of app for the iPhone where you can choose the IP codes you want to use before a call? Would save me and I'm sure millions, if not billions lots of time.

Thanks,
Alexander