an Important note here!
RJ-11 / RJ-14 your standard telephone cord, typically use from phone to wall jack same size connector, but one is a single line 2 pins used while the other is a two line four pins used.
RJ-45 standard 8 pin, used for various connections, ethernet being the one we're most used to.
While it's true that a RJ-11 or RJ-14 plug will fit inside a RJ-45 jack. I do NOT like to see it done. looking at the RJ-45 jack, you will see the two outside pins that will not be used with the smaller RJ11/14 plug.
Now look at that plug, see the outside square shape? the two corners are going to bend the outside pins of the RJ-45 jack, likely to a point where they will no longer work, as in broken, forever.
( as an aside, where I've seen this is when a computer gets hooked up as someone's home by someone who doesn't know which connectors go where, and they think the ethernet connecor is for the phone line, it'll fit, but the network card is not likely to work afterwards.
With that said, IF the two outside pins on the RJ-45 are never used for anything, then go ahead and plug in the RJ11/14. Better to make a cable for that device connection.
