There is disclosed a system and method for transferring a mobile handheld device between mobile carriers. In an embodiment, a system for transferring a handheld device between mobile carriers comprises a provisioning system for receiving from a first mobile carrier a request to register the device on the first mobile carrier's wireless network; a database uniquely identifying the device to determine if the device has been previously registered; deactivation means for deactivating the device from the second mobile carrier's wireless network if the device has been previously registered to a second mobile carrier; and registration means for registering the device on the first mobile carrier's wireless network upon confirmation that the device has been deactivated from the second mobile carrier's wireless network. The device may be uniquely identified by a unique electronic serial number (ESN) or a unique product identification number (PIN).