Using Cat5 for phone, terminating in RJ11

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 Question by Jim Barton posted 21 Dec 2005
 Using Cat5 for phone, terminating in RJ11
We are moving into a new office that has been star-pattern wired with cat5 cable, mostly terminated in RJ45 female plugs. I need to take the two phone outputs from two Vonage adapters, which are single line each, and combine those so that the cat5 cable becomes a two-line telephone cable. It seems that as long as I use the same wiring patterns at each end, this would be possible. Is there hardware that would easily accept two RJ11 connections from the Vonage adapters and put them into a two-line format into cat5 cable? And then would there be an adapter cable that has RJ45 on one end and RJ11 on the other for connecting the wall outlet (RJ45) to the phone (RJ11)? I think I could wire this all myself, but was hoping someone sells these adapters so all I would need to do is make sure I connecte the right lines at the Vonage adapter end and use the already existing terminations at the wall.
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 Answer by Joseph Golan posted 21 Dec 2005
Dear Jim,

This may be easier then you think but it will depend on is the category 5e cable was terminated in a T568A or a T568B pattern.

The 2 line version of an RJ-11 is actually known as an RJ-14. If you have two line telephone, they most likely have this input. The T568A will mate up exactly for the first two pairs so if that is the case all you will need to do is get a two line splitter and just patch it in to take the two lines from Vonage and combine them into a single two-line jack. A two-line splitter is commonly available and changes a 2-line RJ-14 into 2 single line RJ-11s.

If you cabling was terminated using the T568B wiring scheme this will present a little more difficult problem. While pair 1 on the T568B will mate directly with pair 1 of the RJ-11 or RJ-14, it is actually pair 3 of the T568B jack that aligns with the 2nd pair of the RJ-14. In this case you would need to wire your own adapter to accomplish this.

If you need more details on this, either re-post with my name in the subject (so someone else doesn't restart with you, or contact me directly by email and I will make a quick diagram and email it back. In either case let me know if the cat 5e terminations are T568A or T568B (hint - look at the back of the jack for the color codes used), also let me know if the telephone you are going to use do have an RJ-14 or 2 RJ-11 (look at the user guide for this info or send me the model of the phone and I'll try to look it up.

Sincerely,
Joseph Golan, RCDD

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