Modes Of Operation; Cut-Through Mode; Senderized Mode - Avaya Communication Server 1000 Series Reference

Overview
When a switch serves as an intermediate (tandem) connection between trunks, it normally
sends the supervision signal it receives from each incoming trunk to the connected outgoing
trunk. It also monitors for a disconnect signal so the trunks can return to an idle state and wait
for new calls.
In some cases, no provisions are made for returning an answer supervision signal from the
destination when the called telephone answers. If this occurs, an off-hook signal can be
returned from an intermediate switch. This off-hook signal is called "substitute answer
supervision." This signal is provided to remove transmission impairments associated with the
on-hook condition on some trunk facilities and to distinguish a call that has been blocked from
one that might have reached a destination party.
A connection by a PSTN trunk is a typical case where a called telephone answer indication is
not returned. The circuit switch that connects the call to the PSTN trunk must be configured to
provide an off-hook signal to the incoming trunk after sending digits to the PSTN trunk.

Modes of operation

A circuit switch can operate in one of two modes when routing a call over a TIE Trunk:

• cut-through mode

• senderized mode

The following sections define these two modes.
Cut-through mode
With cut-through mode, a trunk is accessed immediately following an access code.
Subsequent digits are forwarded to the trunk as dialed. The telephone end user monitors call
progress tones from connected switches. Because of a blocking tone, the end user may be
required to pause during dialing to listen for a dial tone, or may be required to abandon the call
before completing dialing.
Pure cut-through mode provides the greatest flexibility for providing compatible operation for
calls originating at main and tributary switches. The number of digits transmitted to the node
can be flexible. The node can prompt for additional digits when required for the authorization
code features.
Senderized mode
With senderized mode, all digits of the called number are collected before an outgoing trunk
is accessed. The trunk is accessed and digits are transmitted to set up the call. The transmitted
digits need not be the same as those dialed, for example, as a result of NARS digit
manipulation. The end user does not receive call progress tones until all digits are transmitted.
18 Electronic Switched Network Reference — Signaling and Transmission
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August 2011