Re: How to send the person calling a busy signal.

I have an 84-year old friend who lives in another town.  Now that he's
moved, he only has a cell.   Today I called him and after a few rings,
he seemed to anseron hut I only heard a couple "uh"s and then got a busy
signal.
 
What can the person receiving a call possibly do to give me a busy
signal once he has answered, or even before he answers???