I have two phone lines in our home. One regular and one FAX/ Internet. When I built the home I had two jacks (one each) placed behind Home Theater. Now have FIVE lines hooked to those lines using those cheap splitters and everything works fine. If interested:
1 DirecTV Tivo
2 Hughes DirecTV E-86 HD Receiver
3 VOOM Receiver
4 UTV
5 Phone Ringing RS (cheap) orange light (great when you can't hear anything but what's on TV and this light starts flashing!)