Adapt RJ11 jack to RJ45

Posted on 2007-08-02
Last Modified: 2013-11-09
I just moved into a new home, which is a rental. I have discovered that the telephone jacks are wired with CAT5 cable. I do not intend to get a landline phone, and I would like to set up a home network using the cable already in place.  I know that for data only 2 of the twisted pairs are used. I have already tried to make an adapter cable with one end having the RJ11 plug, and the other having an RJ45 plug. For whatever reason, it didnt work. I am wondering if this is do-able and am I just doing something wrong? Thanks in advance,

Question by:kyletehgreat
    LVL 95

    Expert Comment

    by:Lee W, MVP
    Just because it's wired with Cat5 doesn't mean it's wired for networking.  Phone systems often have the same pair of cables essentially spliced together at all jacks.  If your place is like this, you would have major problems because the signal would be going to EVERY outlet.  AT BEST, you MIGHT be able to network TWO devices... no more.
    LVL 7

    Accepted Solution

    Depends on if two pairs have been punched into the socket (assuming a 4contact connection) and whether they followed correct standards.

    There are really two options - either they will have used blue and orange pairs (A spec) or blue and green (B spec) ... now the blue pair (centre pins usually used for voice) are not used in 100BaseT spec .

    have a look at - your RJ11 jack will probably use (effectively) pins 3,4,5,6 as the terminals - if you wire approporaitely - AND the cabling is consistent between the jacks (making sure that the cabling ONLY goes POINT TO POINT (and not split out anywhere) this should help.

    You could of course, if you can trace which cable is which, buy RJ45 face plates and module, and replace the RJ11 ones.  This requires little skill, and should be unnoticable if you move out and change them back again.

    Good Luck!!!!

    Author Comment

    THanks for the input. I realized my mistake and it was in the pinout of the wall jacks. Once I corrected this--It worked. I was happy. Thanks again.

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