US Patent 7706253 Gateway to route communications during a fault

Telephones connected to a gateway can still make calls when connectivity to a central processing device is lost. The gateway determines when connectivity with the central processing device is lost. When a communication is received from a first telephone for second telephone, the communication is routed to the second entity by bypassing the central processing device. This is possible using identification information that is stored for the second entity when the second entity registered with the central processing device.