"This standard defines the stage two of the pan-European Integrated Services Digital Network (ISDN) as provided by European public telecommunications operators for the Terminal Portability (TP) Supplementary service. Stage two identifies the functional capabilities and the information flows needed to support the service as description. The stage two description also identifies user operations not directly associated with a call (see CCITT Recommendation I.130 [1]). This standard is specified according to the methodology specified in CCITT Recommendation Q.65 [2]. This standard 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 this standard does not specify the requirements where the service is provided to the user via a private ISDN. This standard 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. This standard 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 relative terminals should provide at the man/machine interface the capabilities for: - Suspension of the call(s) - Resumption of the call(s) - Indication of the phase of the call(s) (i.e. active phase and suspended phase) as long as the terminal remains plugged in. The TP supplementary service does not apply to non-interactive services such as facsimile@ teletex@ mixedmode@ 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. This standard is applicable to the stage three standards for the ISDN Integrated Services Digital Network TP supplementary service. The term ""stage three"" is also defined in CCITT Recommendation I.130 [1]. Where the text indicates the status of a requirement i.e. as a strict command or prohibition@ as authorisation leaving freedom@ as a capability or possibility@ this shall be reflected in the text of the relevant stage three standards. Furthermore@ conformance to this standard is met by conforming to the stage three standards with the field of application appropriate to the equipment being implemented. Therefore no method of testing is provided for this standard."