SSH EN 301 484-1 V1.1.1:2000

Integrated Services Digital Network (ISDN); Line Hunting (LH) supplementary service; Digital Subscriber Signalling System No. one (DSS1); Part 1: Protocol specification

Scope

The present document specifies the stage three of the Line Hunting (LH) supplementary service for the pan-European
Integrated Services Digital Network (ISDN) as provided by the European public telecommunications operators at the
T reference point or coincident S and T reference point (as defined in ITU-T Recommendation I.411 [13]) by means of
the Digital Subscriber System No. one (DSS1). Stage three identifies the protocol procedures and switching functions
needed to support a telecommunications service (see CCITT Recommendation I.130 [7]).
The present document does not specify the additional protocol requirements where the service is provided to the user via
a telecommunications network that is not an ISDN.
The LH supplementary service enables calls to a single ISDN number to be offered to a free access in a group of
accesses to which terminals are connected.
The principles for the selection of a free channel within an access are a network provider matter as part of the basic call
procedures and so are outside the scope of the present document.
The LH service is applicable to all circuit-switched telecommunication services with the exception of services requiring
the use of more than one B-channel.
Further parts of EN 301 484 specify the method of testing required to identify conformance to the present document.