The Figure 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 1.2.3.4.5.6.7.8.9.4.3.e164.arpa.
2. A request is sent to the Domain Name System (DNS) asking it to look up the ENUM domain 1.2.3.4.5.6.7.8.9.4.3.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.

Designed by myself, User:Abasota, using Visio

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Moved from English Wikipedia, original upload history:
(del) (cur) 16:24, October 24, 2006 . . user:Abasota (Talk | contribs) . . 999×479 (35,376 bytes) (ENUM Application scenario Author: user:Abasota Drwn using Viso)
(del) (rev) 15:22, October 24, 2006 . . user:Abasota (Talk | contribs) . . 999×479 (43,115 bytes) (Drawn using Visio, by User:Abasota)
(del) (rev) 15:21, October 24, 2006 . . user:Abasota (Talk | contribs) . . 999×479 (43,029 bytes) (Drawn using Visio, by User:Abasota)
(del) (rev) 14:54, October 24, 2006 . . user:Abasota (Talk | contribs) . . 999×461 (44,131 bytes) (To illustrate how ENUM works. Designed by myself, User:Abasota, using Visio)

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