On that topic, I find it interesting to see how different medium/regional scale ISPs have developed their own in-house GIS systems, once they reach the size and scale where one FTE staff position to run GIS systems/database backend is a necessity.
There is a great deal that can be done with QGIS and entirely GPL/BSD licensed software, if your GIS person has a background in this sort of thing.
Privately hosting a intranet-based tile-server for openstreetmap data and overlaying your own network on top of it is not extremely difficult.