cellphone signal repeaters
I think it's pretty cool that you can purchase cell phone repeaters for your home or office. This actually isn't a bad solution if you want to get rid of the landline but have crummy reception in your hacienda.
CellAntenna.com sells these things and I don't think the prices are that unreasonable.
these things are what they install at trade shows so you can get reception in the basement of the Sands hotel in Las Vegas, etc.
this is certainly a little bit gearhead but could be the answer to all your problems.