There is disclosed a system and method for enabling text messages to be sent from a computer to a mobile device, and for a reply text message to be sent from the mobile device to the computer. An outgoing text message, including a reply telephone number, is sent from a source computer to a destination mobile device. The reply number that is sent is chosen on the basis of regions (either geographic or regions associated with particular mobile communications providers) with the reply number being “leased” for use with a particular outgoing message. A protocol exists for choosing an alternate reply number if the first choice is not available. Means are then also provided for forwarding a reply message received by receiving means associated with a reply number to the source computer.