Some devices will scan for open wifi networks in the area and connect to those if you don't give them your own network. It's also entirely possible they have de

Some devices will scan for open wifi networks in the area and connect to those if you don't give them your own network. It's also entirely possible they have deals with ISPs to use the router you rent from them on a separate network (some routers in the US broadcast a 'public' paid wifi network that's separate from yours that anyone can connect to and doesn't count toward your data).