New Communication Technology Promises "A Single Number for all Services"

On 23 January DENIC has switched the administration of ENUM domains over to regular operation. Following a successful trial phase, in which around sixty companies and numerous other interested parties were involved, and a positive appraisal by Germany's Federal Network Agency, the new full-scale ENUM service is now available to anyone holding a telephone number in Germany. It is possible to arrange for registrations through many of DENIC's members.

The term “ENUM” is derived from “telephone number mapping”. It is a protocol defining how to link together resources from the telecommunications and Internet spheres. It sets out a rule by means of which a telephone number can be uniquely mapped to a domain. This domain can then be used for the identification of various communication services, such as telefaxes, cell phones, voice-mail systems, e-mail addresses, IP-telephony addresses, web pages or call diverts. For users, ENUM and the services associated with it, open up the whole world of communication through their standard telephone numbers. ENUM is also used for linking different voice-over-IP networks.

From a technical point of view, what is involved is establishing a linkage by mapping and registering a domain that corresponds to a telephone number. Taking, for example, the number +49 69 27 2350, this would be assigned to an ENUM domain called 0.5.3.2.7.2.9.6.9.4.e164.arpa. Under the domain, it is then possible to enter records of the various communication channels actually available to the domain holder, and queries about these can be submitted via the Internet. Instead of having to grapple with lots of different numbers and addresses for private, office and mobile phones as well as telefax, e-mail and websites, which demand a really big effort just to keep them up-to-date, it is going to be possible in future to enter just one single number per person in our address books. Making sure that each communication is routed to the appropriate output device is then going to be handled by the entries in the ENUM name server.

The linking of telephone numbers and Internet resources is leading to the creation of totally new services. One basic service is finding an Internet terminal with telephony capability from a conventional telephone. As an option, it is possible with ENUM to draw callers’ attention to alternative communication channels that are actually available. If no Internet device with telephony capability is available, the caller will be able to select an appropriate alternative from the list of additional applications presented.

ENUM is also frequently used to establish connections between voice-over-IP terminal devices residing in different provider networks. This avoids the situation where telephone calls across network borders would have to revert to the conventional telephone network, which would cancel out the cost benefit of Internet telephony.

One of the main things that customers wishing to use ENUM will notice with the move into regular operation is that they will have an increasingly wide choice of new product solutions from ever more suppliers. Currently, more than sixty DENIC members are already able to handle requests dealing with ENUM domains, and more than 4,000 such domains have already been registered in Germany. This figure is deceptively low, since one ENUM domain is sufficient for operating whole telephone installations with unlimited numbers of extensions, which means that the number of subscribers already using ENUM is very much higher. One good example is the Saarland University in Saarbrücken, which is already using ENUM for all its extensions.

For further information about ENUM please visit http://www.denic.de/de/enum