They do not share channels, and cannot talk to each other.  In most cases, a cell phone is better for emergencies, although nothing will work everywhere.  If you get into a canyon or behind the wrong hill, everything quits working.

FSR has a range of a mile or two, while CB is more, if you have a good unit, but both are line of sight.  Cell phone service gets spotty in the mountains as well.

Bill
  ----- Original Message ----- 
  From: Allyn Moore 

  Here's a question; do CB and FRS radios share channels?  Can the two radios communicate?  Since I have been known to hike several miles away from civilization, my spouse would really like it if I could keep in touch with the outside world somehow in case I had an emergency, etc., etc.  I am wondering what might be the best type to carry.