However, once you start walking into the hills behind Trefriw, the signal can deteriorate quickly – varying on location – to a point where a signal can often only be found in the highest spots.
In addition to carrying a paper map, we’re fans of using O.S. 1:25,000 mapping on mobile phones, which will pinpoint your exact location at any point. The O.S. have their own O.S. Mapping app, but Memory Map app is also good. These apps use GPS, not a mobile signal, so will work wherever you go (though you should download the basemap first).