The present invention proposes a method for performing a detach of a terminal registered to a telecommunication network by associating an identification for said terminal, deriving a signature for said identification, and allocating a pair consisting of said identification and said signature to said terminal, said method comprising the steps of: sending a detach request including said identification and said identification signature from said registered terminal to said network; receiving said detach request at the network side; comparing said received detach request with a record of registration data of said terminal kept at the network side; and detaching said terminal from said network, if said received detach request coincides with said record of registration data.