MobiMap doesn't provide its own map data provider. Instead it uses existing mapping data available on the web and you can write your own TileFactory implementation to use your own tile server.
For example, Google Maps offers a JavaScript API and an ActionScript API but no official direct access to their tile server. Please read the different Terms of Service to be aware of the usage conditions of each provider:
Note that MobiMap displays a Copyright Notice on top of all maps using external data. Moreover, since MobiMap is released under a GPL v3 license , it's free and non-commercial and if you use MobiMap in your application, you're legally required to release it under a license compatible with GPL v3.