In order to enhance data link security, the present invention provides a method of calculating a start value for security for a user equipment, or UE, in a wireless communications system. The method includes selecting ciphering sequence numbers, denoted by COUNT-Cs, and integrity sequence numbers, denoted by COUNT-Is, of radio bearers and signaling radio bearers using the most recently configured ciphering key and integrity key, determining a maximum COUNT value of the selected COUNT-Cs and COUNT-Is and calculating the START value when twenty most significant bits of the maximum COUNT value reach a first value resulting from subtracting a predefined value from a maximum value. Preferably, the maximum value is 1048575, whereas the predefined value is 2 or any other positive integer.