The worrying annoyance of phone signal in the UK hills

You're on a hillside, something happens and you need to call Mountain Rescue. You're out of signal for your phone company, but not to worry, a carrier has signal here as you have the "emergency calls only" tab running across the top of your screen.
Wonderful.
Call 999, get through to the police, give them some info, sit-down. Wait.

Now, that is all well and good. 

But what if they want to get back to you? 

What if someone from Mountain Rescue wants to clarify some information? 

It can get pretty damn cold just sitting around and waiting....

What if the information was written.down correctly, but has been passed on incorrectly in a Chinese whisper like chain? (it wouldn't be the first time a 5 figure grid reference got passed to an MRT team)

Well, you're not in signal for your carrier, so no one is going to be able to get hold of you.
Yet... You could call 999 again, and it would go through.... That's crazy, right?

If you were abroad and the phone needs to change carriers in order for you to have signal, it does that automatically. If you are in signal for any carrier, you can make and receive calls and texts without a problem. 

In the UK... Hah, you'd be so lucky. And this is one of those things that we live with here because that's just "the way things are". I find it astonishing both as someone who has called Mountain rescue, and as someone who responds to the callouts as well.

For the moment, that is just the way things are. I think it's insane that someone can call Mountain Rescue but we can't call them back just because they are out of signal with their provider EVEN THOUGH THEY HAVE SOME KIND OF SIGNAL. 

It's the kind of thing that could save a life, save someone pain, or save someone from ongoing long term issues because we haven't been able to get to them as expediently as possible. 

Mountain rescue tried calling... they're going to be a while...

So if you are in that situation, it's worth a second call about 50 mins after your first one just to make sure the information flow is still there.
If need be you can then be transferred on to Mountain Rescue as you're already on the phone... (even though they couldn't call you). As I say. Mental. 

Is there anyway we can change this in the UK? Will the big phone companies listen to reason? Will they even hear about the issue in terms of a life saving possibility?

I doubt it.  

And if you want a more technical viewpoint of all this, head over here---> Haydns blog- where a friend has deconstructed it a bit more.