Future telecommunications systems will introduce a multitude of partly small network and/or service providers. For those providers to interwork, a coordinated organizational cooperation and standardization of the technology are crucial. One important aspect of standardization is about handling user identities. In the Daidalos architecture, users and user groups are considered equally. As there will be a multitude of identities per user, identity management is of utmost importance in modern telecommunications systems. Standardization in this area should comprise formats of user attributes of an identity representation, identity information exchange protocols and security standards for handling identity data.