Nortel 1000 Features And Services Fundamentals page 560

560 Conference
Conference Control disconnects an unwanted third party (trunk only) from a
three-party conference. Analog (500/2500 type) telephone users implement
this feature by means of switchhook flash. Telephones with the six-party
conference capability implement Conference Control by dialing SPRE + 87.
It is recommended that all analog (500/2500 type) telephones have either the
three-party conference (C6D) Class of Service or the six-party Conference
(C6A) Class of Service to avoid confusion when using Conference Control.
Operating parameters
Due to the possibility of getting annoying noise (squealing, for example)
when two or more trunks are involved in a conference, it is strongly
recommended that no more that two trunks be involved in the process.
At least one party in the conference must be a telephone on the local
system for the duration of the conference call.
Attendant Administration does not support the implementation of six-party
conference for analog (500/2500 type) telephones. An error message is
displayed if an attempt is made to remove Transfer Allowed (XFA) Class of
Service for analog (500/2500 type) telephones with a C6A Class of Service.
A Transfer allowed (XFA) Class of Service is required for a three-party
conference (C6D) and is also a prerequisite for the six-party conference
Class of Service (C6A) on analog (500/2500 type) telephones.
Dial access of Conference Control is provided only for analog (500/2500
type) telephones with a C6A Class of Service.
The number of time slots is limited to 30 per conference loop. For Small
Systems, a maximum of five simultaneous conferences, each consisting of
six conference users, is supported per conference loop.
Double conferences are blocked to avoid conference chains (that is, set
A and set B are on an established call. The user of set B presses the
Conference key to call set C. Any attempt by set C to initiate another
conference is blocked if set B has not yet completed the conference).
While the originating side of a call is linked to a transfer or conference key
(that is, the originator of a transfer/conference call has not yet completed
the transfer/conference), the terminating side cannot initiate a transfer or
conference. Conference calls cannot be transferred.
Copyright © 1994–2008, Nortel Networks
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Nortel Communication Server 1000
Features and Services Fundamentals — Book 2 of 6 (C)
NN43001-106 02.04 Standard
Release 5.5 9 May 2008