A method for managing user terminal identification information is described. In response to an invitation message to establish communication between terminals, a first address identification of a terminal, included in the message, is examined. Based on the first address identification, a first number identification for the corresponding terminal is retrieved from an ENUM database. Based on the retrieved first number identification, a second number identification maintained for the user terminal is retrieved from an MNP database. It is checked whether the number identifications correspond to each other. Based on that, a second address identification corresponding the second communication number identification is retrieved from the ENUM database, and the invitation message is forwarded towards a recipient user terminal such that the second address identification is included in the message.