There is now available a "Master..you have a message" file for download as a ring tone (or maybe its an SMS alert - whatever)
Why not go the whole way and produce a cell phone case mod kit which converts phones into little Barbara Eden 'I Dream of Jeannie' dolls.
Astound and amaze your business
associates with the little voice calling you from your briefcase, then turn them green with envy by saying 'Thank you Jeannie' and placing your personal Jeannie on the table as you take the call. Hang up and Jeannie says "Will that be all Master?" before going back into standby mode.
For the ladies, a handsome and buffed Genie case mod, who calls you "Mistress" in a deep sensual tone.
Oystercase cell phones could have special little servos that mimic a slight bowing action as the call is completed.