MERLIN LEGEND Communications System Release 6.1 | Issue 1 |
Network Reference 555-661-150 | August 1998 |
1 Introduction | |
Tandem Trunking and Tandem Switching | Page 1-6 |
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Tandem Trunking and Tandem Switching1
The term tandem switching describes the process of routing an incoming call over an outgoing tandem trunk or PSTN facility. If the outgoing trunk is a tandem trunk, it connects to another system in a private network. When the call terminates at an extension on a non-local system, it is an intersystem call. Release 6.0 provides enhanced underlying capabilities to satisfy recommended levels of voice and data quality over tandem trunks in a private network.
A tandem-switched call does not necessarily terminate at another system that is directly connected to your own. It may travel over the private network to yet another networked system. Furthermore, a non-local system may direct the call to a PSTN facility and then to someone located outside the private network.
For example, from a system in Minneapolis, a long-distance call to an outside party in Boston can be routed over private tandem trunks to another system in Chicago and then to a system in Boston, resulting in a local call. This routing requires that the private network sites be connected using either a delay-starttie line (analog or T1-emulated) or a digital T1 circuit that has been programmed for PRI.
Figure 1–1 shows one way that systems can be connected in a private network.
NOTE:
All of the figures in this chapter use the following conventions:
■A solid line represents a tandem trunk that connects one system in a private network to another system in a private network.
■A dashed line represents a facility that carries a call to the PSTN.
■A square labeled ML indicates a MERLIN LEGEND Communications System.
■A rounded rectangle labeled DEF indicates a DEFINITY ECS or DEFINITY ProLogix Solutions system.
