scope:

This first part of ETS 300 662 specifies the stage three of the Multiple Subscriber Number (MSN) supplementary service for the pan-European Broadband Integrated Services Digital Network (B-ISDN) as provided by European public telecommunications operators at the TB reference point or coincident SB and TB reference point (as defined in ITU-T Recommendation I.413 [1]) by means of the Digital Subscriber Signalling System No. two (DSS2) protocol. Stage three identifies the protocol and procedures and switching functions needed to support a telecommunication service (see ITU-T Recommendation I.130 [2]).

In addition, this ETS specifies the protocol requirements at the TB reference point where the service is provided to the user via a private B-ISDN.

This ETS does not specify the additional protocol requirements where the service is provided to the user via a telecommunications network that is not a B-ISDN.

The MSN supplementary service provides the possibility for assigning multiple numbers to a single public or private access.

NOTE: This allows e.g.:

1) a calling user to select, via the public network, one or multiple distinct terminal applications out of a multiple choice;

2) to identify the terminal application to the network for the application of other supplementary services.

It is considered:

- that some service providers may not have knowledge or control over what is connected, e.g. a private B-ISDN or a terminal configuration;

- that service providers have differing numbering methods.

The MSN supplementary service is applicable to all telecommunication services.

Further parts of this ETS specify the method of testing required to identify conformance to this ETS.

This ETS is applicable to equipment, supporting the MSN supplementary service, to be attached at either side of a TB reference point or coincident SB and TB reference point when used as an access to the public B-ISDN.