A method of establishing a secure communications link between a user communications device and a first service communications device; the method comprises the steps of initiating a communications link using a first communications protocol between the user communications device and the first service communications device; performing, based on a PIN value, an initialisation procedure between the user communications device and the first service communications device, the initialisation procedure resulting in an identification key; storing the identification key in the user communications device and the first service communications device; the method is characterised in that it further comprises the steps of using a second communications protocol to perform a transaction between the user communications device and a second service communications device; generating and storing the PIN value; the invention further relates to a communications system and a mobile communications device.