Abstract: The present invention provides a hand held electronic device, which includes a near field communication element located proximate a top of the device, that is adapted for being selectively enabled. The hand held electronic device further includes a user identification sensor, which in at least some instances is a further near field communication element, and is adapted for confirming the identity of an authorized user of the device. The user identification sensor is located in a user holding area at a back side surface of the device. The user identification sensor is adapted for sensing a user interaction in an area proximate the back side surface of the device and receiving as part of the interaction, user identification information corresponding to a particular user presently using the device, and determining whether the user identification information corresponding to the particular user matches identification information for a predetermined authorized user.

Abstract: A digital network based communications system that establishes communications sessions to communicate via a simulated circuit-switch environment. Exemplary embodiments communicate between a first communications station (104) and a second communications station (106) using Voice over Internet Protocol (VOIP) techniques. Calls are setup (700), maintained and torn down (800) using Session Initiation Protocol and Session Description Protocol messages. Call modes are able to be changed between duplex and simplex without disconnection. Duplex calls are also able to be interrupted with a request for a simplex call. A receiver (104) engaged in a duplex call can receive a request for a simplex call, accept the simplex call or send a response message, and then resume the duplex call, all while maintaining the duplex call data communications session.