Numbering guide · Global services

DID, Toll-Free
& ITFS Numbers

Number types, routing, capabilities, compliance and procurement for carriers and international businesses.

Rightech SolutionsUpdated 15 September 2026Technical reference

Availability is destination-specific. Number type, reachability, voice or SMS capability, permitted use and documentation vary by country, operator and provider.

01

Number types explained

DID / DDI

A number that routes inbound calls to a defined endpoint without requiring a dedicated physical line for each number.

Geographic number

Associated with a city or area code; local-presence or address conditions may apply.

National number

Reachable nationally without necessarily representing a specific city.

Mobile DID

Uses a mobile numbering range; voice and SMS support depends on the country and network.

Toll-free number

Charges for eligible inbound calls are paid by the receiving customer rather than the caller.

ITFS

International Toll-Free Service allows callers in a specific originating country to reach a service paid for by the receiving organisation.

02

How calls are routed

The public network receives a call to the assigned number and passes it through the numbering provider’s interconnection. The service can then route it to an authorised SIP trunk, PBX, contact centre, IVR or forwarding destination. Routing design should define number format, CLI treatment, codecs, capacity, failover, emergency limitations and testing.

03

Capabilities to confirm

Inbound voice

Reachability, concurrent-call capacity and supported origins.

Outbound presentation

Whether the number may be presented as CLI and under which verification rules.

Inbound SMS

Whether messages can be received and delivered through the supported interface.

Outbound SMS

Whether the range supports compliant originating traffic.

IVR and forwarding

Destination choices, conversion charges and geographic restrictions.

Portability

Whether an existing number can be ported, with what documents and lead time.

04

Compliance and responsible use

Provisioning may require company records, end-user identity, proof of address or local presence, intended use and supporting service information. Approval is not automatic. Numbers must not be used for impersonation, deceptive caller identity, fraud, abusive traffic or prohibited communications.

  • Identify the legal end user and beneficial business purpose
  • Confirm local-presence and documentation requirements
  • Verify permitted voice, SMS and CLI use
  • Maintain accurate records throughout the service lifecycle
  • Monitor traffic and respond promptly to abuse reports
05

Procurement checklist

Before ordering, specify countries and cities, number type, expected traffic, concurrent channels, SIP endpoints, voice/SMS direction, CLI requirements, redundancy, desired activation date and end-user documentation. Ask separately about setup, recurring, usage, forwarding, porting and regulatory charges.

Important: “Global coverage” never means identical functionality in every destination. Obtain written confirmation for each country and capability before designing the customer journey.