This page explains DID numbers as they are used in business and wholesale telecoms — the numbers that carry inbound calls into phone systems, contact-centre platforms, and carrier networks. It does not cover consumer privacy apps or disposable "burner" numbers, which are a different product with different rules.

A DID number is often used interchangeably with the term virtual number. The word "DID" comes from telephone-system engineering; the plain-language market now applies it to almost any number you buy online and route yourself.

How does a DID number work?

A DID number works by mapping a public phone number to a routing instruction you control, instead of to a dedicated wire. When someone dials the number, the call travels across the PSTN (the Public Switched Telephone Network — the traditional global phone network) to the carrier that holds the number range. That carrier hands the call to your provider, who sends it to you as a SIP (Session Initiation Protocol — the standard signalling used for internet calls) message carrying the dialled number.

Your PBX (Private Branch Exchange — the phone system that switches calls inside an organisation) or softswitch reads that number and decides where the call goes: a specific agent, a queue, an IVR menu, or an external forward. Because the routing lives in your system, one number can reach one person or an entire team, and you can change the destination without touching the number itself.

Where the term "DID" comes from

Direct Inward Dialing was originally a PBX feature. Before it, a company had a handful of physical lines and a switchboard operator connected each caller to an internal extension by hand. DID let the carrier deliver the dialled digits to the PBX so the system could route the call to the right extension automatically — many published numbers over a shared set of lines, no operator in the middle.

As phone systems moved to the internet, the same idea detached from physical circuits. "DID" now usually means a number you order from an online inventory and receive over SIP — which is why, in everyday use, "DID number" and "virtual number" describe the same thing.

What a DID number is not

A DID number is not an extension. An extension is an internal short code (like 204) that only has meaning inside your phone system; a DID is a full, publicly diallable number that reaches your system from the outside. A single DID can point at an extension, but they are different layers: the DID gets the call to your system, the extension routes it once it is there.

It is also not tied to a device. Unlike a SIM card or a line on a desk phone, a DID is a routing entry in the cloud — you can move it, forward it, or fail it over to a second destination.

Types of DID numbers

DID numbers come in a few forms, and availability varies by country:

  • Local (geographic) numbers carry a city or region prefix and read as local to callers there — the most widely available type.
  • National (non-geographic) numbers give one countrywide identity that is not tied to a city.
  • Toll-free numbers are free to the caller, with the cost borne by the number holder.
  • Mobile-range numbers use a mobile prefix where regulators allow it — useful when traffic expects a mobile origin.

You can see which types are available in each market on the virtual numbers coverage table, and read how the terms fit together in DID vs virtual numbers.

Frequently asked questions

Is a DID number the same as a virtual number?

In most current usage, yes — the terms are treated as synonyms. Where a distinction is drawn, "DID" emphasises the direct route into a phone system while "virtual number" describes any cloud-routed number. Both describe a number provisioned online and delivered over SIP.

Do I need special hardware for a DID number?

No. A DID number is delivered over the internet to a SIP endpoint, so any SIP-capable system — FreeSWITCH, Asterisk, 3CX, FreePBX, or a softphone — can receive it. No new lines or on-site telecom hardware are required.

Can one DID number serve many people?

Yes. A DID can ring a whole team through a ring group or IVR, or map one number to one user. The routing is decided in your phone system, not in the number itself.

Can I keep a DID number if I change provider?

Usually. Number portability lets you move an existing number between providers, subject to the rules of the country and number type. Timelines and documentation vary by market.

Get a DID number

Temptera provides DID / virtual numbers across 100+ countries with instant provisioning and pay-as-you-go pricing — no monthly minimums or lock-ins. Rates are route-specific and shown live once you create an account. Explore the DID numbers solution, check country coverage, or talk to sales about volume.

Common DID destinations include US DID numbers, UK DID numbers, Netherlands DID numbers and Singapore DID numbers.