AT&T AT&T N s i d e r a t i o n s, C i l i t y, S t r i c t i o n s e e Calling Restrictions, 250

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.

C o n s i d e r a t i o n s

Trunks of the same type and Class Of Service may be assigned a (Pooled) Facility Access Code. This provides users with dial or button access to the trunk pool. Trunks may be dial access restricted to reserve them for AILS and button 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-Button 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.

I n t e r a c t i o ns

●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.
● F a c i l i t y		A c c e s s	R e s t r i c t i o n ( s e e “Calling		Restrictions”):			Stations		may	be
restricted from dialing				the CO trunk pool and/or	all	(fifteen)	other	trunk	groups		(as
a whole). Stations so				restricted may still dial out	if	they are	transferred		to	a trunk
by	another	station	not	so restricted.

● Tie Trunks: Refer to the Tie Trunk description.

●Toll Restriction (see “Calling access FX, WATS, or Tie trunks, applies to CO trunks only).

Restrictions”): When toll restricted stations they are not toll restricted (i.e., toll restriction

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