What about 2-line phones

We have two phone lines coming to the house... my number and wife's number. When we re-built the house it was wired so that both lines come into each phone jack and our (cordless phones) are 2-line. We plug the cable from the jack into the phone's "Line 1/2" socket. When the phone rings we push "Line 1" or "Line 2" depending on which lights up.

It that going to work with the Arris gateway if I take the phone cable from the wall in my office and plug it into the gateway? There is no documentation I can find on how this all cobbles together on the Xfinity site.

(For my office I'll have to get a simple splitter so I can run one cable to the Arris and one to my office phone.)