A method of managing identities for use in a mobile telecommunications device in a telecommunications network is described. First of all, an identity management process is triggered. After this, one or more parameters associated with the mobile telecommunications device is detected. The identity management process than has the following features. An identity management rule determined by the one or more parameters is detected. An identity database is then searched. Each record of the identity database comprises an identity and additional identity information for each identity, wherein the searching prioritizes records according to the identity management rule. An identity is then selected when a record conforming to the identity management rule is found in said searching. The active identity of the mobile telecommunications device is then changed to be the selected identity when the active identity is not already the selected identity. A subscriber identity module adapted for use with this method is described.