I've used a cheap Nokia in flight - I couldn't hear unless I put it under my headset, but the guy phoning me heard what I said. With an earphone it would have worked O.K. I've all the likely Scottish Airfield numbers in my phones memory.
I carry a handheld and a headset adapter - I once had to use it without the headset adapter, and I had difficulty hearing, but was heard O.K. Noise was a problem even when throttled back. With the adapter it's as good as the fixed radio.
If you're not on radar, 7*00 would be pointless, but you probably are on several even at low level over Orkney.
The ultimate solution is to land at a strip, keeping a good look-out. L*******??