RJ11 to RJ45

We had the same problem and nearly went "bananas" looking for this "magic adapter". Then we googled "RJ11 to RJ45", the title of this thread by chance and got it amongst the hundreds of other "hits". That's where we learned that RJ11 plugs "fit" inside RJ45 jacks....ergo...yes go hunt for an "adapter".

But then the "light bulb lit up" and we made measurements comparing RJ11 6P4C jacks to RJ45 8P8C jacks, (P = "positions", C = "conductors"), found that the ONLY difference was in their width, .375 inches vs .450 inches, all other dimensions were exactly the same, "especially the pitch between conductors/grooves. We quickly got out our handy little "Dremel" rotary tool, inserted a "flat cutter/router" and "evenly narrowed" both sides of both ends of a 25 ft RJ45 network cable until they fit into an RJ11 socket. Replaced the 25 ft phone cable betweem modem and phone jack with this modded RJ45 network cable and "bingo"...it works. No need for any performance degrading adapter, or female/keystone jacks cum short RJ11 wires. And done carefully, the outer conductors are not exposed...even if they were, they are not used.
Thanks guys for redirecting my thought processes, and this post is my payback.

BTW, another "hit" later took me to
en.wikipedia.org/wiki/RJ-45 where we found that the "true RJ45" was originally an 8P2C connector for phones, while the current network "8P8C modular connector" is now erroneously called "RJ45". Interesting worthwhile read. Thanks again all.
candjac

Hi,

I have ADSL broadband conection and my modem has only RJ11 cable and my wireless has only RJ45 port, so can i use RJ11 to RJ45 adapter to connect modem with wireless router?

Regards,
M REHMAN

Agh, I hate always having to create an account on a forum to post. Slashdot had the brains to allow anonymous postings even though I have an account there.

Anyways, dchri mentioned that Most RJ11 connectors have 4 wires and most RJ45 connectors have 8. Lemme clearify this a little. RJ is a jack only with pins. Wires connect to the pins (See USOC). Now RJ11 only has two pins and always two, if it has less then 2 it is not an RJ11 jack. Most people confuse this because lots of people refer to plugs which are not RJ11 as RJ11 when most like they are RJ14 (4 pins) or RJ25 (6 pins). Most common phone jacks use an RJ14 with a compatible plug that supports two lines. Red and green wires, respectively ring and tip points, make up the first line and yellow and black, respectively ring and tip make up the second line. Additionally you can crimp cat 3, 5, 5e and 6 to an RJ14 or RJ 25 jack where blue makes line one, orange makes line 2 and green makes line 3.

Also RJ45 is 8P8C or 8 pins 8 connectors and therefor if it does not have 8 wires crimped into the RJ45 then it is a broken RJ45 port.

dchri also posted a diagram with white and blue not used. It's orange and blue, tip and ring, and they are used for RJ25.