A method of managing identities for use in a mobile telecommunications device in a telecommunications network has the following features. The identity management process is triggered and one or more parameters of a currently available mobile telecommunications network detected. An identity database is searched—each record in the identity database comprises an identity and additional identity information for each identity. The additional identity information includes the one or more parameters. The identity management process involves selecting an identity when a first record comprising the one or more parameters detected is found in said searching and modifying an active identity of the mobile telecommunications device to be the selected identity when the active identity is not already the selected identity. This process can be carried out by a subscriber information module of a mobile telecommunications device.