@gedankenstuecke This will often be carrier dependent. In the US, for example, Verizon and AT&T often have good signal on rural ridge lines while T Mobile does not, and sometimes only one of the three will have a signal. I don't know if it is feasible to include all those details on OSM. I suppose all of the cell towers could be mapped, if that info is available, so hikers might be able to figure out how to get within range of one.