In my area (Rockford, IL) they run one line to a little grey box on the outside of the house, it goes through a grounding block and then to a two way splitter, one cable is labelled (phone - which is a lie) and goes to the cable modem, the other goes to a 3 way splitter to the TV lines. If they come, they may disconnect the three way splitter (or equivalent) and put a lock on the two way splitter, which is easily removed (they did this to my Mother in laws even though she has Basic cable??).
As an aside, it is cheaper here to get internet + basic tv ($9 local qam channels only) that just internet as they then charge you for a one service only fee of $15. We get our landline through Nettalk which is about $30 per year for unlimited calling over VOIP.