I agree with the above...

You mentioned people keep asking too much - what are they asking you to do?

There are polite ways to decline...
I have a meeting (ok so it is with yourself)
Screen all calls (if they won't leave a message then I guess they didn't need what ever they thought they needed)
If your like most cell phone only - put it on silience or as InACorner says "rip the phone of the wall"

Trying careful not to tell you what you should do...just giving suggestions that at the moment may be overlooked and may be worth considering?