thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Collaboration, Voice & AV · Foundational

Direct Inward Dialing (DID)

A carrier service that routes external calls directly to individual internal extensions without an operator.

Definition

With DID the carrier delivers some or all of the dialed digits to the enterprise, and the call control system maps them to internal directory numbers, often through translation patterns or significant digits on the trunk. DID ranges are assigned in blocks by the provider. Users also present DID-based external phone number masks as caller ID on outbound calls.

Example

The carrier delivers +14085551234, and CUCM strips to the last four digits to reach extension 1234.

Exam tip

DID handling usually involves inbound digit manipulation such as significant digits, prefixes or translation patterns.

Related terms