maintaining end-to end synchronization on a telecommuncations connection

Method for maintaining a synchronization end-to-end on a telecommunications connection transmitting data in frames substantially in real time and using a synchronized encryption end-to-end, in which, based on the number of frames received in the receiver of the telecommunication connection, end a value of a vector corresponding to a received frame and used in decrypting the frame initialization is defined, and wherein at least a part of the telecommunications connection is a connection packet switched, characterized in that the method comprises: increasing the reproduction delay of data being transmitted in the receiving end of the connection packet switched adding one or more extra frames to the frame string being transmitted , make a frame to be added to increase the reproduction delay as an extra frame, and the number of frames received, counting only the frames not marked as extra frames.