| 摘要 |
A special host routing code is transmitted from the remote switch to a host switch which advises the host switch whether the call is to be made to a subscriber local to the host switch or to a remote subscriber via an external telephone system trunk connected to the host switch. In the set up of a call, two steps are executed in addition to those of a normal switch-to-switch communication which functions to set up a path from the remote switch through, or to the host switch. These steps are the outpulsing of a host routing code from the remote switch over a specified trunk to the host switch and waiting for an acknowledgement, such as a wink (temporary line open or close condition). This causes the host switch to set up a cut-through path through the host switch, allowing the remote switch to tandem through the host switch. The digits dialed by subscribers on both switches to affect similar types of calls are therefore similar, and similar types of switches can be used for the remote and host switches.
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