Sorry but that's rubbish, been dealing with that stuff for longer than I care to mention.
As I said they are the same modular family and so compatibility is the name of the game. Variations between manufacturers are the only issues I've ever come across.

In reply to a post by joconnell:

In reply to a post by Rockh:

Load of tosh about damaging the socket, they are the same modular family.

A bit of google research backed up with advice from an experienced professional does suggest that plugging an RJ11 plug into an RJ45 socket will bend the connecting pins excessively, possibly damaging the socket.

Your "experienced professional" probably does not know his ass from his elbow either. He is talking rubbish. as I and others have said, RJ45 and RJ11 are from the same family and were designed to allow smaller connector to be inserted into the larger sockets. I've been using them for too long - probably since the early 80s and have never heard such a ridiculous claim.

Edited by MHC (Wed 05-Jan-11 00:40:08)

If I am not mistaken you can actually stick a flat head into the port and completely push the pins down till they lie flat with the plastic surrounding and they will still bounce back to their original position. Therefore no way an RJ11 will damage the pins.

Edited by Pipexer (Wed 05-Jan-11 17:45:47)