by which private branch exchanges 304 authenticate affiliated terminal 301 such authentication methods are well known in the art and it will be clear to those skilled in the art after reading this disclosure how to make and use embodiments of the present invention that incorporate such methods it is to be understood that the above described embodiments are merely illustrative of the present invention and that many variations of the above described embodiments can be devised by those skilled in the art without departing from the scope of the invention for example in this specification numerous specific details are provided in order to provide a thorough description and understanding of the illustrative embodiments of the present invention those skilled in the art will recognize however that the invention can be practiced without one or more of those details or with other methods materials components etc furthermore in some instances well known structures materials or operations are not shown or described in detail to avoid obscuring aspects of the illustrative embodiments it is understood that the various embodiments shown in the figures are illustrative and are not necessarily drawn to scale reference throughout the specification to u201c one embodiment u201d or u201c an embodiment u201d or u201c some embodiments u201d means that a particular feature structure material.