IF you want a call back, leave that message.
There are many times when I would not like a callback, so i leave a time frame. If you get this message and can call me back in the next hour, please do. It is now 3pm, pls call before 4pm. Today is Jan 29th, friday. If not please respect my privacy.
That has all the necessary elements, morph it to your own way of doing things and make it friendly. I have never had a problem.
Impt elements are date, time, time frame.