The terminal Portability (TP) supplementary service allows a user to move a terminal from one socket to another within one given basic access during the active state of a call.It also allows a user to move a call from one terminal toanother terminal within one given basic access during the active phase of the call.The portability of a terminal during the idle state is part of the basic access capabilities and does not require any procedure.The portability of a terminal in the call establishment and in the call clearing phases is not possible.