Having served on Mountain Rescue in Scotland in my younger days, when I was still in my 20s over 50 years ago, I heartily concur that Radio is a necessity for this service. In my days, the 1950s, the portable radio weighed in at around 70lbs, whatever that is in new money,and if you drew the short straw you were lumbered and you lost wieght and mobility when you had the antenna erected. Can't remember the frequency but it relied on something like 10 feet of copper sticking up to get signals and was unreliable over greater distances than 800 yards. Today's technology means that it is possible to pack a more reliable set of gear into a pocket sized piece of equipment and I have, personally, a set of four handsets which I used when taking my granddaughters out so that they could be in contact for any possible emergencies. They are m obile phones and are usable up to a couple of miles apart with great reliability, dependant on the surrounding terrain. On the flat, ie line of sight, I could rely on them for about 9 or 10 miles and frequently used them at this distance. No hassle regarding frequency allocation or payment for an imagined service as I was using the assigned frequency and could/can vary the actual frequency required by varying amounts in order to use the band more effficiently and get more signals in plus, I could issue specific frequencies to each girl so that I knew with whom I was in contact. At about £50:00 per set it was, I thjopught, money well spent.