Technical question- improving cell signal

I didn't see a technical forum, so I put this question here. I am in a semi rural area although there are cell towers near me. For some reason I just can't get a good signal in my house. The best one gets one, maybe two bars during the day, but the signal is likely to drop completely at anytime during the call. If I drive down the road a bit the signal is really strong.

My question...is there any way to reliably boost a cellphone signal? Such as with an antenna? I have only tried the prepay phones could that be the problem?

If I talk to the salespeople they are just going to tell me whatever it takes to sell me a plan, so I thought I would take a shot and ask you guys.