Method to synchronize at least one mobile unit to at least one base transceiver station belonging to a digital telecommunication network, in which radio signals transmitted and received by said base station are subdivided in frames (Fn) having pre-determined duration and each frame is subdivided in a pre-determined number of timeslots (Tn) and codes (Cn), said signals including at least a synchronization signal (S), which is transmitted by the base transceiver station and includes a sequence of modulation elementary units suitable to identify the timeslot (T1) and the code (C1) of a service channel containing system messages (M), said method including the following operational steps: marking the synchronization signal (S) in at least one frame (Fx) by the base transceiver station; transmitting a pointer message (P) in the service channel of said frame (Fx) or of a subsequent frame (Fx+n) by the base transceiver station; detecting the marked synchronization signal (S') by the mobile unit; receiving the pointer message (P) by the mobile unit; extracting from the pointer message (P) the position of at least one system message (M') by the mobile unit. The present invention relates also to a system implementing this method.