I am surprised in this day and age, MRT's don't have a "radio" that allows communication to a mobile phone. Imagine a casualty on a mountain with a mobile but out of range of the nearest mast. I would have thought it possible to a radio that acts like mobile mast and establish Comms to the casualty's mobile...if such a device was too heavy to carry, it could be perhaps vehicle mounted, or even in the SAR helicopter....
There is research and development going on to produce a product like this that we are aware of. It is mostly driven by Rescue Teams locating casualties via their mobiles in avalanches etc. We have seen some prototype products which look interesting. Usually we can ring a casualties mobile if they have signal and we have some phone find technology that will give us their grid reference.
I would expect it is because there isn't often a good enough cellular signal where they are. Rural areas have worse signal because in places of beauty like the Peaks people don't want unsightly mobile phone towers. There are 'network radios' out there that rely on cellular as well as some that cover DMR as well as cellular use, but are probably not as durable as those sorts of radios. Because the have to work in the worse weather the country has to throw at us and carry on working.
