INTERNATIONAL TELECOMMUNICATION UNION ITU-T RECOMMENDATION SUMMARY Rec. No. : Q.83.4 Title : Stage 2 description for call completion supplementary services Study Group : XI - Switching and Signalling Version : New Date of adoption : 1991 Notes : TERMINAL PORTABILITY Recommendation Q.83.4 defines the stage 2 of the integrated services digital network (ISDN) as provided by telecommunications operators for the Terminal Portability (TP) supplementary service. Stage 2 identifies the functional capabilities and the information flows needed to support the service as description. The stage 2 description also identifies user operations not directly associated with a call (see Recommendation I.130). Recommendation Q.83.4 is specified according to the methodology specified in Recommendation Q.65. Recommendation Q.83.4 does not formally describe the relationship between this supplementary service and the basic call but, where possible, this information is included for guidance. In addition, Recommendation Q.83.4 does not specify the requirements where the service is provided to the user via a private ISDN. Recommendation Q.83.4 does not specify the requirements for the allocation of defined functional entities within a private ISDN; it does however, define which functional entities may be allocated to a private ISDN. Recommendation Q.83.4 does not specify the additional requirements where the service is provided to the user via a telecommunications network that is not an ISDN. The 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. 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. The TP supplementary service applies to some interactive telecommunication services requiring the attendance of a human being, such as telephony, videotelephony, etc. However, the network will not take any action to restrict its applicability. The TP supplementary service does not apply to non-interactive services such as facsimile, teletex, mixed-mode, computer communication, etc. The relative terminals should not provide for the above mentioned capabilities. It is a user's responsibility to resume the call with a terminal which is compatible both with the remote terminal and with the type of connection previously established. Recommendation Q.83.4 is applicable to the stage 3 Recommendations for the ISDN integrated services digital network TP supplementary service. To order the complete text of this Recommendation, please use the Order Form for ITU-T Recommendations. An electronic version of this form is available on ITUDOC (Winword 2.0: UPI=ITU-5265; ASCII: UPI=ITU-2488).