International DID numbers: a practical guide

A DID number lets customers in another country call you as if you were local. Here is how they work and what to plan for before ordering.

What is a DID?

DID stands for Direct Inward Dialing. A DID is a real telephone number on the public network that, instead of ringing a physical line, delivers incoming calls to a VoIP system — a PBX, contact center platform, softphone or SIP trunk. One business can hold DIDs in many countries and answer all of them from one place.

Number types

• Geographic (local) numbers are tied to a city or area code. Callers in that area usually pay a local rate.
• National numbers represent a country rather than a city.
• Toll-free numbers are free for the caller; the number holder pays per minute, often at different rates for fixed and mobile callers.
• Mobile numbers are available in some countries and may support SMS.

How an inbound call reaches you

1. A caller dials your number in, say, London.
2. The local carrier delivers the call to the number provider.
3. The provider converts the call to VoIP and sends it over SIP to the destination you configured.
4. Your PBX, IVR or contact center answers and routes the call.

Because routing is configured in software, you can change where calls go — a new office, a different queue, an overflow team — without changing the number.

Regulation and documentation

Many regulators require that numbers are assigned to identifiable end users, sometimes with a local address. Typical requirements include:

• Name, business name and contact details
• ID or passport, and company registration documents for businesses
• A local address in the number’s area, with recent proof of address
• A signed end-user registration form

The local carrier reviews these details, and the number may not be activated until they are approved. Requirements change, so always confirm them for each country before you promise customers a launch date.

Planning checklist

• Which countries and cities do your customers call from?
• Do you need local, national or toll-free numbers — or a mix?
• Where should calls be delivered, and how many simultaneous calls do you expect?
• Do you need outbound caller ID or SMS on the same numbers?
• Who in your organisation will supply registration documents?