A method and a system which enables a User Equipment (UE) in a Universal Mobile Telecommunications System (UTMS) to achieve fast dormancy in least possible time are provided. The method reduces the signalling burden on UE and Universal Terrestrial Radio Access Network (UTRAN) by eliminating the need of SCRI procedure by introducing cause value as ‘end of user data’ in Cell update cause Information element which can be used in cell update message in a Paging Channel (Cell_PCH) state and a UTRAN registration area (URA_PCH) states indicated to the network. The method reduces the time and signalling to transition the UE to an idle mode time and the method is energy efficient.