ENUM is the short name for a protocol for connecting resources of telecommunication and the Internet to one another. It specifies a rule that makes it possible to relate a domain to a telephone number without any risk of ambiguity. This domain can then be used to identify various communication services like fax, mobile radio, voice-mail systems, e-mail addresses, IP telephony addresses, web pages, GPS coordinates, call diverts or unified messaging. Several countries in the world examine the possibilities of the use of ENUM in national trials. Recently two Hungarian universities and an Internet service provider established a research project aiming the development of ENUM based communication services. In Hungary we have to deal not only with the questions of creating and providing the technological background, but also with the business aspects of ENUM based service development. The article will firstly give an overview about the ENUM itself. Then it will deal with ENUM services and business models. After that we discuss the situation of ENUM in different European countries. It will present the planned and accomplished ENUM based services in these countries. Then we are going to give the aims of the project in Hungary, which is led by the Szechenyi Istvan University in Gy6r. In setting these aims we can rely on the projects of other countries, and learn from them. © 2005 IEEE.