Have fun with your captive audience!  Captive?  How so?  Develop a message that gains attention by being unique, creative, and differentiates you from the competition.  Be enthusiastic!  Leave a message highlighting success, how you did it differently than the competition or current supplier.  Leave your call back number twice.  Write out your number as you say it to slow you down so the person listening to it can hear it.  

A sales professional I knew used these tips and created twenty appointments in less than one week.  She hadn’t been able to schedule one appointment.  She also hated cold-calling during the day.  She wanted to speak with only truly interested individuals.  What did she do? She left interesting messages at their place of work late at night that would create an eagerness to call her back the next morning (Just be sure their office is not their home as well!).

 “Creativity is a natural extension of our enthusiasm.” 
-Earl Nightingale