A cellular radiotelephone (10) includes a keypad (22) having a plurality of keys (22a, 22b) and a display device (20) for displaying information, including messages, to a user. A method includes the steps of: (a) transmitting a short message service (SMS) message from a network (32) to the cellular radiotelephone; (b) receiving the SMS message from the network and storing the message in a memory (24) of the cellular radiotelephone; (c) presenting the stored SMS message to a user; (d) determining if the presented SMS message requires a manual acknowledgment by the user and, if so, monitoring an output of the keypad to detect a single key depression by the user. The method further includes a step of (e) determining if the user's single key depression is a correct manual acknowledgement and, if so, automatically generating and transmitting to the network a SMS manual acknowledgement message that includes an identification of the single key depressed by the user.