Can I use a phone jack splitter to connect modem to wall and then wall to phone?

the instructions say to plug the modem directly into a phone itself  but I want to connect all phones throughout the house to the voice service instead of just one. Can I use a phone jack splitter to connect the modem to the wall jack via splitter--which would connect all phones in different rooms that are plugged into the wall--and then connect the phone itself to the wall jack via same splitter--and have all phones in the house connected to xfinity voice?