AT&T AT&T manual 127

DIRECT INWARD DIALING (DID)

Description

Allows incoming calls to reach specific individuals or facilities in the system without attendant assistance.

System 25 customers reserve blocks of DID numbers from the CO. The DID numbers may correspond to a PDC FPDC, DGC access code, DDC, or any facility with an access code such, as a pooled facility or a paging zone.

The system is capable of	receiving	either 1,	2, 3, or 4 digits over its DID trunks. The number
of digits received on a specific DID trunk			will be constant for that	trunk; however, different
DID trunks may receive	different	numbers	of digits. The system is	capable of receiving U P
to four digits and then ignoring leading			digits as specified to match against system dial
codes. For example, the	dial code	matching	DID number NXX-2157	can be 57, 157, or 2157.

If the System 25 is administered to match on more digits than are received from the Central Office (CO), the additional leading digits are taken from the 4-digit trunk number. For example: if a call comes in on DID trunk number 1234, the CO sends two digits (77) over this

trunk to identify the recipient, and System 25	is administered	to match on three	digits, then
the call will be routed to dial code 277.
Incoming DID numbers that don’t match any	valid dial code	may optionally be	directed to
the Attendant Console or to Reorder Tone.

If the DID number received is a valid dial code, the caller is provided either Ringback Tone, Busy Tone, or the tone from a pooled facility (e.g., Dial Tone) as soon as addressing is completed. Busy Tone is provided if and only if the call cannot be completed to the intended voice terminal and cannot be provided coverage.

DID calls appear at System Access buttons on multiline voice terminals (they do not have other button appearances). These calls can be transferred to a covering station, answered via Call Pickup, directed to a DGC Group, or given “call hunting” or “call following” treatment. A DID call is not automatically covered on the Attendant Console.

DID trunks may utilize DID Immediate Start or Wink Start protocols. Refer to Section 9, Glossary, for a brief description of each of these trunk types.

Considerations

Direct Inward Dialing frees the attendant from handling certain incoming calls.

Interactions

●Attendant Camp-On: DID calls are not provided Attendant Camp-On treatment. They will not appear on the Direct Trunk Attendant Console Return-On-Busy or Return-On-Don’t-Answer buttons or on the Switched Loop Attendant Console Loop buttons unless they are first answered at the attendant position and are subsequently extended by the attendant.

●Attendant Direct Extension Selection: Selector Console LEDs respond to DID

calls just as they do for other outside calls. When a user answers a DID call, the associated LED on the Selector Console will light steadily. When a DID call arrives at the attendant position for coverage, the LED associated with the call coverage

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