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MERLIN LEGEND Communications System Release 6.1
Network Reference
555-661-150
Issue 1
August 1998
Introduction
Page 1-14Tandem Trunking and Tandem Switching
1
■ In this configuration, System B uses more of its 80-line capacity for private
network trunks than do Systems A, C, and D.
■ A centralized VMS/AA is installed on System B. Voice mail and automated
attendant services can be used by extensions and calling groups on
Systems A, B, and C. Since Systems A and C are connected to System B
via a PRI tandem trunk, Message Waiting light updates are sent over the
signalling D-channels. The call information signals sent by Systems A and
C to the centralized VMS/AA on System B allow the centralized VMS/AA to
differentiate between inside and outside calls. Some applications (such as
Intuity AUDIX) use the information to play different personal greetings
recorded by users for inside and outside callers.
■ Since System D is not directly connected by a tandem trunk to System B,
System D must have its own local voice mail system and automated
attendant.
The configuration illustrated in Figure 1–4
, with its advantages and
disadvantages, is suitable for many businesses, particularly when one or more
systems do not require PRI features. For example, a system linked by tandem tie
trunks may be perfectly adequate for a warehouse or other operations group.
Figure 1–5. Star Configuration: Three Systems
PSTN
PRI
PRI
PRI
PRI
ML A
GS
ML C
ML B
V o ic e M a il/A u to A tte n d a n t
GS