Lucent Technologies 555-661-150 manual P R I M L C

MERLIN LEGEND Communications System Release 6.1	Issue 1
Network Reference 555-661-150	August 1998
1 Introduction
Tandem Trunking and Tandem Switching	Page 1-14

■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.

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Figure 1–5. Star Configuration: Three Systems