What does ENUM mean?

What does ENUM mean?

People often use the term ENUM in discussions about VoIP, but what does it refer to and why should anyone care? It stands for telephone number mapping. It is a simple four letter acronym representing a monumental idea: being able to use the same phone number no matter where in the world you are.

If you visited this page looking for enum (enumerated data type) instead of the ENUM protocol, please refer to this page.

How does ENUM work?

To put it simply, ENUM unifies the international public switched telephone network (PSTN) with internet addressing. This works by translating standard telephone numbers into internet addresses (URL or IP address). Servers that support ENUM will search any dialed number in the ENUM tree of the DNS to locate substitute ways to setup a call outside of the standard PSTN telephone line.

What are the types of ENUM?

In terms of classification, there are three types of ENUM:

  • Public User  – This version allows the end-user to manage their own account and enter their own records into the registry.
  • Private Infrastructure – This type is used by a specific group without using the public domain. This group creates a domain name for each telephone number and links it to a uniform resource identifier (URI).

  • Public Infrastructure – This final type is centrally managed by a National Number Administrator. This authority delegates a telephone number to a carrier, which in turn assigns the telephone number to an end-user. The carrier maps telephone numbers to an internal network of addresses in order to enable call routing. This type of is the most protected as only service providers have access to the information.

    Rules for ENUM numbers

    The owner of each number has the ability to publish their number and choose rules for how the call should be routed. This could be one rule for a call from a fax machine and another from a phone. The protocol requires the specific support from the phone of the caller.

    How do you register an ENUM number?

    A number is registered much like how you would register a domain. At present many registrars and VoIP providers are providing this as a free service. To complete the process, registration must go through a registration service such as Ripe with the standardized ENUM request form. The registrar sends this to the International Telecommunication Union, Telecommunication Standardization Sector, Telecommunication Standardization Bureau (ITU-T TSB). After this the number is registered and ready for international use.

    New but growing standard

    The standard is still new and hasn’t gained wide adoption yet. Though it looks to become another revolution in communications and personal mobility. As more and more providers utilize it the mobility of workers and individuals alike will be greatly increased and costs will continue to decrease.