A free "cell phone" for use within a few miles of home?
ab9rf: Assuming the US, you'll run into legal problems.  None of the Part 15 (low-power unlicensed) bands would have the range you're looking for; the power levels are too low to give that much range.  Part 97 (ham radio) wouldn't help; there are too many restrictions on content (no encryption, no profanity, no pecuniary interest, limits on "third party" traffic, etc.) to use ham radio for the purpose desired.  And you can't send data (other than selective calling codes, and geolocation bursts only in the FRS) on the various licensed-by-rule "citizen" services in Part 95.That pretty much leaves you with having to get a business radio license ($260 per ten years minimum, plus possible additional fees), and on top of that you'll need a someone with a GROL ($60 fee plus testing fees) to maintain and operate it.The only other option would be unlicensed VLF.  This you could do, but there's two problems: the antennas for VLF are huge, and the available bandwidth is tiny.  Ever used a 300 baud modem?  Well, that screams compared to what you can get out of a VLF connection: 5 baud is a fast data rate in this band.Those Voyager units use frequencies reserved for military use the United States.  Using them in the US would be a good way to get yourself in a heap-o-trouble.The problem you have is that for the range you want you need to be able to operate over the horizon.  That means your receiver is going to be in one of the transmitter's diffraction zones, which means only a fraction of the transmitter's signal will get through.  We do this all the time in radio, and we accomplish by throwing enough power at the problem to have a received signal strong enough to be demodulated even with diffraction losses.  For the distance your looking for, you'll need about 25 watts minimum, way more than you can get away with in Part 15.