Phoca Maps maps can be displayed with help of Google Maps or Open Street Map.
Open Street Map:
Open Street Map (Humanitarian):
Open Street Map (OpenTopoMap):
Open Street Map (Germany):
Open Street Map (France):
Open Street Map (Black and White - be aware, this map type is currently not working. We are waiting for what will happen with this project, if it is deactivated, this option will also be removed from Phoca Maps):
There are even other types: Mapbox, Thunderforest (API key is needed) or Wikimedia (may be unavailable).
Project page: Phoca Maps plugin