Data transfer verification based on unique id codes

A method of transferring a data packet from a providing communication terminal to a requesting communication terminal, wherein the requesting communication terminal transfers a message to the providing communication terminal including a requests for receiving the data packet and a first unique identification code identifying the requesting communication terminal. Upon receipt of the message the providing communication terminal verifies the validity of the first unique identification code. When the verification has been ended successfully, the providing communication terminal responds by transferring a message to the requesting communication terminal including the requested data packet and a second unique identification code. Then the requesting communication terminal verifies the validity of the second unique identification code and stores the data packet accordingly when the verification has been successful.