Ham radio walkie talkies are great for maintaining contact among scattered hikers and by SAR teams. Radios with GPS can be tracked and seen live on http://aprs.fi either by knowing their callsign, or just zooming into an area.
This Spring, hope to consider getting a number of Hams to section hike and develop a coverage map for those that follow. I'm wondering if there are any others interestred in participating? Also on July 23rd each year for 4 hours we try to communicate from Springer to Katahdin using 14 hikers on top of 14 mountains covering the entire 2170 miles. See http://aprs.org/at-golden-packet.html
Apology: We do use earphones so as to not bother anyone else. Sorry, its just that altitude gives range, and that's what we like to do. P.S. always works and is not dependent on cell phone networks. Bob, WB4APR