It doesn't look like they do any more though, in my quick searches. But maybe I missed it.

There are various antennas and amplifiers that exist for situations like yours, but you might need to climb up on the roof and/or put up a pole to get a decent signal. If you've got lots of trees, as I think you do, the pole might need to be very high indeed...

I'd start with your cell service provider and see what they say. Chat might be less aggravating than sitting on hold for 30+ minutes, or fighting with their web page to find a support e-mail address...

Good luck!

Cheers,
Scott.