solution to poor phone signal?

[globetrotter]

Has anybody had problems with a low phone signal strength and found a reasonably cheap solution. Lots of people have to go up a hill or can only get a signal in a certain spot or some such.
I'm especialy interested in someone using a smartphone trying to get internet access. There are aerials and boosters on the market but they are very expensive.
Please let me know how you've got over the problem.