RJ-45 to RJ-11 cable



  • So, i'm setting up a new home office. There are no RJ-11 jacks in the room, if possible I'd like to tap into some of the pre-existing and unused RJ-45 connections in the room. Telephony modem will be housed in the server room right next to the data modem. I was hoping I could build 2 cables as pictured below. One going from the RJ-11 telephony modem to the RJ-45 patch panel whose wires run through the walls up to the office. Then another cable from the wall plate in the office with RJ-11 connections to the telephone handsets RJ-11 connection. I see no documentation of anybody else on the net doing this, and I have limited knowledge in the area of telephone communications. What I did find was that blue is generally used as Line1, orange as line2, and green as line3, when using standard category cabling. I will only have 1 line coming from the modem so obviously orange and green would be useless to use, but since I am makign the cabling myself and have an excess of Cat5, I might as well include them so that they may be functional in the future without re-cabling if the need arises.

    Please let me know if this theory will work. If not, instruct me on how I should make these cables, or if it is easier to run new wiring. for an RJ-11 jack.


  • Rebel Alliance Developer Netgate

    It may work but it would be super confusing. Why not just replace an RJ45 jack with an RJ11 jack? Rewiring the jack isn't hard, and then you won't have to even remember which is a data port and which is a phone port or keep special cables around.

    Alternately, an RJ11 plug will fit into an RJ45 jack, so just wire it up like an RJ11 at the jack. Still confusing, but less confusing than needing a special cable. Just remember to label the jack appropriately.

    The next person who has the house after you may want to shoot you either way you go, though. :-)