Surgery Waiting is one of my more popular placements because of the sustained interaction with patients and visitors.  We use restaurant pagers that vibrate and flash only when you dial the number.  Each family is assigned one as they register and urged to keep the pager until the patient has been discharged or sent to a in-patient room.  We page them if the doctor wants to see them or to provide updates when the patient moves from OR to PACU.  The volunteers simply hit the speed dial to reach the pager's pre-recorded message and enter the two-digit pager number which then dings the pager.  They stack and recharge while plugged into a simple AC adapter, so we just keep them right on the desk and the numbers are written on the pager.  The volunteers keep a list of which families have which pager.