System and method for determining whether an incoming call originates from inside or outside of a mobile carriers network and indicates the result to the subscriber. An example system performs a GTT (global title translation) on an incoming number to determine the hosting carrier of any mobile phone number. When the result matches the subscriber's carrier, the mobile device then indicates to the subscriber (i.e. mobile device) that the call is an “in network call.” Results of the comparison are stored and used for later incoming calls. The stored results are refreshed every time or periodically.