The new service bridges the gap between the Internet and telephony - a single number suffices for all services

The ENUM project has now taken on a new momentum thanks to the signing of the agreement concerning a test operation to be run by DENIC eG.

The name "ENUM" is a short form derived from the term electronic numbering or, alternatively, from telephone number mapping. It is an Internet standard that is used to map telephone numbers onto Internet domains. These domains can then be used for the storage and identification of various communication services. Examples are call numbers for fax and mobile telephones, voice mail systems, e-mail addresses, IP telephony addresses, web pages, GPS coordinates, call diverts, unified messaging and much more. Thanks to ENUM and ENUM services, users gain access to the whole world of communica-tion by means of their established call numbers.

Whilst the international ENUM standards and recommendations are still being worked on, DENIC, the registry for .de domains, has been running a test ENUM operation since September 2002. This is being accompanied by Reg TP (the German regulatory authority for telecommunications and posts), one of whose functions is to administer the German numbering system in accordance with § 43 of the German telecommunications law (TKG). This test operation provides a platform for the development of services and equipment for this new technology and for testing their robustness in practice.

In order to accelerate the process of developing ENUM in Germany, DENIC and Reg TP have now agreed to place the field test on a more formal basis and to intensify their joint endeavours. In so doing, the two institutions, each one of which has extensive expertise in its own particular fields of activity, want to give further impetus to the development of ENUM in Germany. DENIC's contribution is its know-how and experience in the administration of domains, whereas Reg TP is accompanying the test operation with its expertise in the field of telecommunications. Two things are already known for certain: ENUM will only function if there is an assurance of the precise mapping of allocated telephone numbers and if a level of data protection can be established that end users will find acceptable.

"ENUM is an extremely promising project, which is opening up uniform access to the varied world of communication. This is widening competition between alternative means of communication for the clear benefit of consumers," remarks Matthias Kurth, Reg TP's President.

"ENUM is an attractive service to offer and we want to help it achieve market maturity as soon as possible in the interests of the German ITC industry," is how Sabine Dolderer, a member of DENIC's Executive Board, describes the reasoning underlying the agreement that has now been concluded. "The test operation is open to anyone interested in joining in, in order to test the ENUM applications in a near-practical environment and to develop them further."

Backgrond: ENUM - a single number for all services

The idea behind ENUM is both marvellously simple and fascinating. Instead of having to juggle with a multiplicity of numbers and addresses for office and private telephones, mobile phone, fax, e-mail and web page, which take a major effort to keep up-to-date, it is going to be enough in the future to enter a single number in an address book. Routing messages to the appropriate output devices is then the job of the entries in the ENUM name server.

ENUM does this by using the Domain Name System (DNS). The DNS establishes logical connections between the numeric IP addresses of the computers and domains connected to the Internet. The ENUM protocol then uses the DNS infrastructure to hold information concerning the available services that are assigned to a particular telephone number. Internationally, it has been decided not to introduce any new top-level domain for ENUM but to use the subdomain e164.arpa. The reason for this choice is that the top-level domain .arpa has already been devised for infrastructure purposes. "E164", on the other hand, is the designation for the standard that describes the ITU's international call-number plan. It is RIPE NCC in Amsterdam that is functioning as the international registry for e164.arpa and which is handling registration requests in liaison with each national government concerned.

In order to form the ENUM domain, the relevant telephone number (including the E164 country code) is placed in front of the subdomain e164.arpa in reverse order with dots between the individual digits. Thus, 0.5.3.2.7.2.9.6.9.4.e164.arpa results from +49 (0)69 27 23 50. An ENUM client can transit through this domain to access a nameserver with so-called NAPTR (naming authority pointer) records. In turn, these records contain the information on the services available. "Thanks to the use of the tried-and-tested DNS with its clear hierarchal structure, the whole process is very transparent and open, as well as being technically mature, flexible and attractively priced", describes Sabine Dolderer, member of the DENIC board, the advantages of ENUM. Since the ENUM protocol basically does no more than define a translation rule, the services on the provider side can be enhanced at will at any time.

In agreement with the relevant bodies, the trial run for the German part of the ENUM name tree (i.e. 9.4.e164.arpa) has been delegated to DENIC, which, as the registry for .de-domains has accumulated many years of technical and administrative experience in the field of domain administration. "In the context of this trial run, which has now been underway since September 2002, the intention is to work out an operational model for ENUM with the involvement of all the groups concerned", says Matthias Kurth, President of the Regulatory Authority for Telecommunications and Posts. There is a need, for example, to develop procedures to ensure that only the actual holders of a telephone number can use the corresponding ENUM services. For that reason it is only German telephone numbers that actually exist that are eligible for registration as ENUM domains.

DENIC has set up a web page for the provision of further general information. Its address is: http://www.denic.de/enum. It also documents the details of the whole procedure. Information about the regulatory body and, in particular, the administration of call numbers is to be found at: http://www.regtp.de.

 1 Input of the fax number (+49 1234) of the subsrciber at the sending device.

2 Request of the sending device at the ENUM DNS server using the ENUM domain (4.3.2.1.9.4.e164.arpa) of the dialled number.

3 Answer of the ENUM DNS server delivers a list of possible communication items, among them the information to which URL (ifax:fax@denic.de) an incoming fax message has to be sent.

4 Establishing a connection via the Internet between the sending and the receiving fax device.