What is DID (Direct Inward Dialing)?
A DID (direct inward dialing) number is an external phone number that rings one specific person or team directly, without the caller going through a switchboard or menu.
Before DIDs, reaching someone inside a company meant calling the main number and being transferred. A DID gives that person their own published number while the organisation still shares one underlying set of lines.
DIDs are bought per number and are the usual cost line in a phone system after per-user licensing. Most businesses give every employee an internal extension, which is free, and buy DIDs only for people who regularly receive outside calls.
In many markets DIDs are allocated in blocks, so a company holds a contiguous range. Matching the extension to the last digits of the DID — number ending 4842 becomes extension 4842 — removes one thing for staff to remember.
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