What is an ENUM in Networking?

I am here (again) to know about the ENUM. I have tried to search it on web, but I got details about the enum that are used in programming languages. I want to know about an ENUM (tElephone NUmber Mapping) concepts that are used in telecommunications and networking technology, especially for linking. Actually I have recently started learning about the telecommunications for linking number of systems. It would be more helpful for me if you members provide some detailed information about the topic.

ENUM is a protocol that allows the resources of the telecommunications and networking technology to link together. Specifically, ENUM allows the conversion of telephone numbers in an Internet address, or vice versa. In practice, one would specify only a single contact address rather than a whole list of contact options, such as phone number, fax number, e-mail address or phone number. All the data and more are stored in an ENUM directory that is maintained by the user. The addresses stored there to cover all possible forms of electronic contact, which there is currently and it is perhaps in the future. For example, even instant messaging.

The rest of the contact addresses in ENUM directory is the storage in the DNS (Domain Name System) the same. This decentralized storage and organization has already proved to be advantageous for domain names. The existing and stable DNS is the most important prerequisite for ENUM introduce cheap and fast way. DNS is already implemented everywhere. The infrastructure is based on a distributed database, which ensures the stability and availability of the system. Depending on the application used to examine the terminal via the ENUM telephone number is the correct address. From a regular phone number then a so-called Fully Qualified Domain Name (FQDN). Since a domain is always read from right to left, from the telephone number +49 7141 9914211 ENUM phone numbers 1.1.2.4.1.9.9.1.4.1.7.9.4.e164.arpa. The ENUM protocol uses DNS for the ENUM telephone number to a resolve on the service or the application of correct address. According ENUM protocol can be used in the Domain Name Server special entries for various contact options. This is called the Naming Authority Pointer Records (NAPTR). For each domain, multiple NAPTR records to make and set different priorities.

E.164 is a standard of ITU (International Telecommunication Union). In it, the rules for international dialing plan are set for telecommunications. The ENUM protocol developed by the IETF (Internet Engineering Task Force). To get in on ENUM DNS existing access, the IAB (Internet Architecture Board), the domain e164.arpa proposed. To mimic phone numbers in ENUM phone numbers, the numbers in reverse order as subdomains of the domain e164.arpa be prefixed. Due to insufficient safety measures, it is possible unauthorized tampering with ENUM records and make intercept e-mails or phone calls or to use a foreign account in order to shift the cost to its owners. Stealing from other phone numbers is a major problem with ENUM. Usually phone numbers are unique to a phone line. In IP networks, the telephony device to be connected at any point.

The following description is made by ENUM a connection between a landline phone and a computer:

1. A fixed-line phone dials a phone number.
2. The selection information is forwarded to a gateway.
3. From the gateway the information on an IP network are routed to the gatekeeper.
4. The gatekeeper converts the phone number into an ENUM telephone number in the form of e164.arpa around and makes a DNS request.
5. The DNS server resolves the ENUM address to an Internet address and provides the gatekeeper returns the result.
6. The gatekeeper provides the gateway returns the Internet address.
7. The gateway routes the call to the IP telephony-enabled computer (PC).

For VoIP customers and users is of interest primarily to public ENUM server. Even without SIP provider could operate VoIP telephony for free. In order to operate the public server, the number sovereignty basic requirement and the domain assignment and validation of the data. Large network operators are not interested in ENUM. Internet providers who want to offer their customers telephony lends itself to an ENUM directory as peering with other platform providers. If new providers to then talks to the VoIP customers in the IP networks are kept. The telephone network then remains on the sidelines. Substantially simplifies the VoIP ENUM routing and reduces the complicated procedures for the acceptance Interconnection (Talk By switching between network operators). For example, individual interconnection agreements would disappear, because the interconnection of the network operator via ENUM represents a data exchange node.

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For example, individual interconnection agreements would disappear, because the interconnection of the network operator via ENUM represents a data exchange node.

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I am elaborating an example (provided by "Zeverto"), so that you can understand properly. As the number of the ENUM subscriber is noticeable positive effects on the IP routing. The more participants there are in the ENUM directory, the higher the hit rate. Then more calls within the IP networks maintained and customers can benefit from the cost savings. However, the number of ENUM directories are kept small, usually caused by multiple queries, longer response times in setting up the talks. For the customer has an ENUM server, the address of all addresses and services. It can even assign priorities. For example, a fax sent directly to the e-mail address. Or e-mail comes out on the fax if the e-mail server is unreachable. Provided that the development has not progressed.

You may be interested in a newly created exchange service for private ENUM servers. If you operate an ENUM server, you can list it at
Your ENUM server will be queried along with others by any user of the system when they are attempting to place a call. This way the call will be routed directly to your VOIP server without the help of an intervening telephone company.