A memory device comprises first memory block having first boundary cell and second memory block having second boundary cell. The comprehensive signalling node includes a signalling interface adapted for transmitting and receiving signalling communications and a storage system configured to store a Media Gateway Controller routine, to store a Session Initiation Protocol routine, to store a Session Border Controller routine, to store a Push-To-Talk routine, to store a H. An environment is provided which allows a user to quickly and efficiently switch between service provider accounts supporting communications. In one approach, interconnections can be in arbitrary directions.