J.J.
I would go onto the cell phone provides website. I know that T-Mobile has a few "dead Zones", but I was able to go onto their site and find out where there was coverage.
Here is an example from T-mobile http://www.t-mobile.com/coverage/pcc.aspx
Here is on from Verizon
http://www.verizonwireless.com/b2c/CoverageLocatorControl...
Good luck.