A method of establishing a cooperative ad hoc network of phone extensions is implemented by the cellular devices within the ad hoc network. First, a first cellular device receiving an incoming call or placing an outgoing call is designated as the master of the ad hoc network and the remaining cellular devices are designated as slaves of the ad hoc network. Second, each cellular device is operated to facilitate a multi-party connection to the incoming call or outgoing call, the multi-party connection including the master and one or more slaves.