In the last two years a variety of concepts for service integration and corresponding systems have gained momentum. On the one hand, they aim for the interworking and integration of classical telecommunications and data communications services, such as telephony, voicemail, fax, e-mail, paging, etc. On the other hand, they are focusing on universal service access from a variety of end user systems, including both, fixed and mobile terminals.Such concepts or systems are designated as unified messaging. Most of the technical problems, resulting from the service integration, have been solved during the last years. However, service personalization is still an insufficiently solved problem of today's unified messaging systems. Different services have to be personalized in different ways.This paper will investigate, how different services could be personalized in a unified way. Therefore, several services, which are offered nowadays by unified messaging systems, will be analyzed. In the second part of this paper, a generic approach for service personalization will be given. For illustrating the introduced approach, the last section describes a first realization.