Patent ID: 8270965

Claim:
A computer-implemented method comprising: receiving, by a first mobile device, a cellular call over a cellular network, wherein the cellular call includes a caller identification (ID) number, the caller ID number comprises a number, at least a portion of which is formatted to avoid collisions between the cellular call and other calls on the cellular network; a number, at least a portion of which is encrypted using a one-way hash of a secret key shared by the server device and the first mobile device; or a combination thereof; determining, by the first mobile device, whether the caller ID number is associated with a server device sending a wake-up call; enabling, by the first mobile device, a wireless fidelity (Wi-Fi) interface on the first mobile device when the caller ID number is associated with the server device sending the wake-up call; and initiating, by the first mobile device, a direct call utilizing voice over internet protocol (VoIP) technology between the first mobile device and a second mobile device via the Wi-Fi interface on the first mobile device.