This IVR diagram sample illustrates how ENUM works by giving an example: Subscriber A sets out to call Subscriber B:
1. The User Agent of an ENUM-enabled subscriber terminal device, or a PBX, or a Gateway, translates the request for the number +34 98 765 4321 in accordance with the rule described in RFC 3761 into the ENUM domain 220.127.116.11.18.104.22.168.9.4.3.e164.arpa.
2. A request is sent to the Domain Name System (DNS) asking it to look up the ENUM domain 22.214.171.124.126.96.36.199.9.4.3.e164.arpa.
3. The query returns a result in the form of so called Naming Authority Pointer Resource NAPTR records, as per RFC 3403. In the example above, the response is an address that can be reached in the Internet using the VoIP protocol, SIP per RFC 3261.
4. The terminal application now sets up a communication link, and the call is routed via the Internet.
This IVR diagram sample was designed on the base of the Wikimedia Commons file: Ejemplo ENUM.jpg. [commons.wikimedia.org/wiki/File:Ejemplo_ENUM.jpg]
"Being able to dial telephone numbers the way customers have come to expect is considered crucial for the convergence of classic telephone service (PSTN) and Internet telephony (Voice over IP, VoIP), and for the development of new IP multimedia services. The problem of a single universal personal identifier for multiple communication services can be solved with different approaches. One simple approach is the Electronic Number Mapping System (ENUM), developed by the IETF, using existing E.164 telephone numbers, protocols and infrastructure to indirectly access different services available under a single personal identifier. ENUM also permits connecting the IP world to the telephone system in a seamless manner." [Telephone number mapping. Wikipedia]
The IVR diagram example "Example ENUM" was designed using ConceptDraw PRO diagramming and vector drawing software extended with the Interactive Voice Response Diagrams solution from the Computer and Networks area of ConceptDraw Solution Park.