This application would be useful to me and I guess many people where I'm from, since my carrier (Telcel) has something they call "Free Calls", but this "Free call" must last less than 4:30 minutes because after that they charge you each minute, so I guess you can imagine it is quite difficult to keep track of the time and keep the costs low (and calls are quite expensive in Mexico, comparing them with the US). If someone could please help me code it or give me an idea how could I try to create an application with this purpose. Thank you very much and happy holidays to all!