Instruction manual

Trunk Groups
● Wink Start—A momentary signal (wink) is sent
trunks).
● Delay Dial—A steady signal is sent to the distant
to receive digits (Tie trunks only).
to the distant switch (Tie and DID
switch and is removed when ready
● Automatic—
No start dial signals are used.
The seizure signal sent or received is
sufficient to route the call (Tie trunks only).
Trunk groups connecting with a local CO, WATS office, or FX office can be ground or loop
start. DID trunk groups can be immediate or wink start. Tie trunks groups can be automatic,
wink start, immediate start, or delay dial.
Dual Tone Multifrequency (DTMF) signaling (touch-tone) or dial pulse signaling can be used
between the System 25 and the far end switch. System 25 can send or receive either type of
signaling required by the distant switch (DID trunks can only receive dial pulse signals). The
type to be used is specified when the associated trunk is administered.
An incoming call can be connected to another trunk, a voice terminal, a data endpoint, an
attendant console, or an announcement. When the call is answered, an off-hook indication is
sent to the serving office.
This signal may be used to initiate the recording of call details
normally used for billing.
Trunks in a two-way trunk group should be translated (at the SAT) in the same order that the
serving office hunts when searching for an idle trunk.
System 25 will then hunt in reverse
order. This reduces the probability that both switches will attempt to seize the same trunk at
the same time.
Considerations
Trunks of the same type and Class Of Service may be assigned a (Pooled) Facility Access
Code. This provides users with dial or direct (button) access to the trunk pool. Trunks may
be dial access restricted to reserve them for ARS and direct access only.
Refer to “Recommended Central Office Trunk Facilities” (Section 5) for an estimate of CO
trunk requirements based on traffic considerations. See the “Pooled Facility-Direct Access”
and “Pooled Facility-Dial Access” feature descriptions for additional information.
Trunks may be reserved for incoming calls (e.g., sales or service department calls) by
specifying this in the (administered) Class of Service code.
Interactions
The following features interact with Trunk Groups.
Direct Group Calling:
Most trunks may be administered so that incoming calls are directed
to a specified DGC group. For tie trunks, only the automatic-in type may be so administered.
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