# Direct Inward Dialing (DID)

## Description

Direct Inward Dialing (DID) allows incoming calls on designated trunks to directly access predefined extensions (or other answer points) on a system. Incoming calls to busy answer points will automatically camp-on.

The DID Service is an optional (newer) direct inward dialing solution where incoming calls are redirected to specified destinations (based on the mapping of DID numbers to their destinations) without using the interim Speed Call System.

## Conditions and Feature Interactions

- The CO from which the call originates must be Centrex-equipped. The Centrex absorbs some of the digits dialed and passes other digits to the system.

- DID calls automatically override Do Not Disturb.

- DID calls can access stations, hunt groups, and attendants.

- DID callers receive ringing tone when the required answering point is on-hook.

- DID callers receive a busy tone if the auto camp-on timer in the Class of Service Options form is blank.

- DID trunks may be programmed to access an installed DISA line.

## Programming

For digital (TI/D4) DID trunks:

- Complete the programming in the following forms:

- Digital Trunks

- Trunk Circuit Descriptor - Digital DID

For analog DID trunks:

- Complete the programming in the following forms:

- Analog Trunks

- Trunk Circuit Descriptor - DID

For all DID trunks:

- Trunk Attributes

- Complete the Dial In Trunks Incoming Digit Modification fields by entering the number of digits from the CO that the system needs to absorb and the digits to insert in their place.

## Device Support

Not applicable

## Operation

None

Related Topics

- Program T1/D4 Trunks

- Program Analog Trunks

- DID Service

- Direct Inward System Access (DISA)