I have since converted many of those Cat 5 runs into ethernet jacks instead of phone jacks.

When I still cared about phone I had a few phones running over spare pairs in ethernet cat5. One was the dialup for the house in the period between the T1 going away and the cable modem appearing.

Reminds me, I should sell the phone system I have; It's half-decent, and I'm in no danger of using it.