The present document defines the stage one of the Line Hunting (LH) supplementary service for the pan-European
Integrated Services Digital Network (ISDN) as provided by European public telecommunications operators. Stage one
is an overall service description from the user s point of view (see CCITT Recommendation I.130 [1]), but does not deal
with the details of the human interface itself.
The present document defines the interworking requirements of private ISDNs with the public ISDN.
In addition the present document specifies the base functionality where the service is provided to the user by a private
ISDN.
The present document does not specify the additional requirements where the service is provided to the user via a
telecommunications network that is not an ISDN but does include interworking requirements of other networks with the
public ISDN.
Interactions with (supplementary) services not listed in clauses 8 and 9 are outside the scope of the present document.
Charging principles are outside the scope of the present document.
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 to an end-user s multiple access group (S/T reference point).
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 supplementary service is applicable to all circuit-switched telecommunications services with the exception of
services requiring the use of more than one B-channel.
The present document is applicable to the stage two and stage three standards for the ISDN LH supplementary service.
The terms stage two and stage three are also defined in CCITT Recommendation I.130 [1].Where the text indicates
the status of a requirement, (i.e. as strict command or prohibition, as aut (...abbreviated)