Lucent Technologies Release 8.2 manual Qsig Centralized Attendant Services, Path Retention

QSIG	B Private Networking
Path Retention	Path Retention is a generic mechanism for retaining a network connection that can be
	used by supplementary services during call establishment.
	The Originating PBX invokes path retention for one supplementary service or for
	several simultaneous supplementary services. Invoking a particular supplementary
	service means retaining the network connection if the Terminating PBX encounters
	the appropriate conditions. The Originating PBX is informed of the reason for
	retaining the connection. It then decides (for example, by consulting the calling user)
	whether to invoke the supplementary service. Under some circumstances in which the
	network connection is retained, more than one of the supplementary services for
	which path retention has been invoked may be applicable.
	Successive retentions of the network connection by the Terminating PBX following a
	single path-retention invocation by the Originating PBX are possible. This is a result
	of different conditions being encountered at the Terminating PBX. When an attempt
	is made to invoke a supplementary service for which the network connection has been
	retained, a further condition can be encountered that can cause the network
	connection to be retained again for the same or a different supplementary service.
	Path retention is specified in terms of a Path Retention entity existing within the
	Coordination Function at the Originating PBX and at the Terminating PBX.
QSIG Centralized Attendant Services
QSIG Centralized	DEFINITY ECS supports two versions of CAS: RLT-CAS and QSIG-CAS.
Attendant Service	The CAS feature enables one or more Branch PBXs to concentrate their attendants on
(QSIG-CAS)

one Main PBX. CAS provides transparency between PBXs of most features that are normally available to the basic attendant service.

RLT-CAS uses an analog RLT network to optimized trunk utilization. QSIG-CAS does not use RLT. By using QSIG Transfer and QSIG Path Replacement or QSIG Diversion with Rerouting, the same optimization as using RLT can be accomplished with QSIG-CAS. Using QSIG CAS, you eliminate the need to have a separate analog RLT network.

All current QSIG features and RLT-CAS features are available with QSIG-CAS.

Potential Drawbacks

There are a few potential drawbacks when using QSIG-CAS:

1 Unlike RLT, QSIG Path Replacement does not work immediately. This means that resources are being utilized longer during QSIG-CAS as opposed to RLT-CAS.

2 Unlike RLT, QSIG Path Replacement is not guaranteed.

3 Like RLT, QSIG Path Replacement does not enable a branch PBX to act as a gateway PBX.

4 No path replacement functionality takes place during or after a conference.

		Administration for Network Connectivity
366	CID: 77730	555-233-504 — Issue 1 — April 2000