A map from the olden-days of web mapping when I worked for a telecoms consultancy.

This is one of our late-vintage maps, from the early 2000s, but we built them in the same way from the late 90s:

By today’s standards, the map is pretty basic, but a large number of network operators across the world embedded these maps in their websites and in-store kiosks.

Credits

Image: I think Collins Bartholomew might have provided the map data (I certainly remember visiting them up in Scotland around that time) and the coverage data is from some Turkish mobile network (which may or may not still exist).