MERLIN LEGEND Communications System Release 6.1 | Issue 1 |
Network Reference 555-661-150 | August 1998 |
2 Call-Handling Scenarios | |
Network Configuration Scenarios | Page 2-19 |
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■Faster Message Waiting Light Updates. For centralized VMS/AA systems in Release 6.1 and later, PRI tandem trunks allow Message Waiting light updates to be sent over the signalling D-channel. With tie tandem trunks, Message Waiting light updates compete with other voice and data traffic for available trunks and touch tone receivers. As a result, Message Waiting light updates may be delayed.
Figure 2–1 on page 2–17 shows some PSTN facilities and PRI tandem trunks in a hypothetical private network that includes two MERLIN LEGEND Communications Systems sharing a centralized VMS/AA. A few extensions are shown so that the scenario can demonstrate how calls are handled and how they display at different types of extension equipment. Sample PSTN facilities are shown to illustrate routing when non-local callers use them or when outside calls are transferred or routed across the private network.
Note the following general facts about this small private network:
■Both systems share a centralized VMS/AA located on System B. This might be, for example, a MERLIN LEGEND Mail application.
■When a caller leaves a message or when a non-local subscriber retrieves all messages, the centralized VMS/AA sends the Message Waiting light updates over the PRI D-channel. If all available PRI tandem facilities are out of service when Message Waiting light updates are attempted, the updates are queued behind any other earlier queued updates and are retained on the central system until a PRI facility is returned to service. Message waiting light updates cannot be sent through the PSTN.
■The two systems are located in different area codes in the same large Mid-Atlantic metropolis. They are not, however, geographically distant or in different time zones. For the purposes of this example, it is assumed that both systems activate Night Service mode at the same time and night service calls are routed to the centralized VMS/AA on System B.
■ARS can be used to route calls over tandem trunks to another system and then out to the PSTN trunks connected to that other system. For example, if a user on System A needs to reach an outside party in the 732 (Holmdel, NJ) area code, the call goes over tandem PRI facilities and then to the PSTN through an outside facility connected to System B; if a user on System B needs to reach an outside party in the 212 (New York, NY) area code, the call goes over tandem PRI facilities and then to the PSTN through an outside facility connected to System A. When the preferred routes are used, toll savings are optimal.
■Coverage for extensions or calling groups on remote systems can be accomplished by sending overflow or coverage to an integrated VMI calling group consisting of a single non-local extension referred to as the “VMI conversion number.” The call is sent over the PRI tandem trunks to the centralized VMS/AA and includes call information signals that indicate whether the call originated as an inside or outside call. When the caller leaves a voice mail message, the centralized VMS/AA sends the Message Waiting light update over the signalling D-channel to the extension at the remote system.
