Abstract: A method and system for least cost routing for mobile telephone calls between the United States and Mexico in such a way so that the call is separated into several call legs and the international portion or call leg is routed via a low-cost or no-cost route independently of the local call legs, essentially achieving an international call with local call rates. This uses a SIM card that automatically identifies any incoming or outgoing call and provides the ability to convert the call from an expensive international and/or roaming call to a local (free) call. Several slight variations are disclosed, and all embodiments have an integrated money transfer service that can be used with a very simple low-cost basic mobile phone using IVR, SMS and voice recognition, or can be accessed via the web or via a smartphone app.