1. ENUM User Guide
  2. Feature Description
  3. Overview

2.1 Overview

The ENUM Support feature enhances the capability to access the Unified Data Repository (UDR) database using the ENUM protocol. The ENUM application in DSR supports the ENUM interface on UDP with the bind9 software.

After receiving ENUM message from bind9 through the UDP interface, the ENUM application queries UDR with ComAgent Connection for the DN received in the message. After getting response from UDR, ENUM application generates the response and send it to bind9 through UDP interface. Bind9 forwards the response to the sender of the message.

ENUM Architecture with DSR

The following figure shows the overall system architecture for the ENUM feature with DSR:

Figure 2-1 ENUM Architecture with DSR

ENUM Architecture

E.164 Number Mapping (ENUM)

E.164 Number Mapping (ENUM) is a Telephone Number Mapping standard defined for mapping of traditional PSTN numbers in E.164 format to IP-based format such as URI. ENUM uses a special DNS record type to translate a telephone number into a URI that can be used in an IP network. ENUM allows Internet-based services, such as E-mail, VoIP, and Voice Mail to be located based on the telephone number. ENUM accomplishes this by placing the telephone numbers into the global Domain Name System (DNS).

The following figure shows an example of the ENUM Tier resolution from a DNS perspective. The ENUM data format begins with a phone number, then reverses the digits, places a “.” between each number, and adds an .e164.arpa root domain that is common across both ENUM and this feature.

Figure 2-2 ENUM Tier Record Resolution

ENUM Tier Record Resolution

ENUM implementation is based on a tiered architecture. At Tier 0 is the RIPE NCC which maintains the e164.arpa zone. Entries in the RIPE NCC DNS server correspond to country codes or portions of country codes and point to the Tier 1 Registry that is the authoritative DNS server for that country code or portion of country code. The Tier 1 Registry maintains records that indicate the authoritative DNS server for individual E.164 numbers in the country code or portion thereof. The Tier 2 Provider for an E.164 number maintains the actual NAPTR records that contain information for specific communication services.