Abstract: A carrying case attaching conventional personal mobile phone instruments on to the forearm or wrist of the phone's user in a manner that permits the mobile phone to be utilized while fastened there is disclosed. The carrying case provides improved security for the mobile phone instrument and greater convenience and reduced risk of loss for mobile users. In particular, the carrying case permits operation of mobile phones for sending and receiving calls without removing the mobile phones from the carrying case and without removing the carrying case from the user's arm. The carrying case includes an arm band that attaches the carrying case to the user's wrist or forearm and a retainer that is affixed to the arm band at one end and removably attached to the arm band at the other end. The retainer is flexible and transparent so that users can actuate switches through the retainer, permitting one-handed use of the mobile phone.