Hi

On another thread regarding networking we got into a discussion on the RJ-11 and RJ-12 connectors, all of my refernce material for A+ (Mainly Sybex) states that they are both 4 pin male with the RJ-11 for Phone connection and the RJ-12 for phone handset connection.

However it appears that others have different definitions, their reference says both conntors are 6 pin male with some stating that the RJ-12 does not really exist.

Can anybody help to clear the situation.

RJ-11
The most common telephone jack is the RJ-11 jack, which can have six conductors but usually is implemented with four. The RJ-11 jack is likely to be the jack that your household or office phones are plugged into from the ordinary "untwisted" wire (sometimes called "gray satin" or "flat wire") people are most familiar with. In turn, the jacks connect to the "outside" longer wires known as twisted pair that connect to the telephone company central office or to a private branch exchange (PBX).

(source)
http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci214238,00.html

I'm not sure if the RJ-12 realy exists...  but I DO know that if I walk into a Graybar and ask for a box of them they will hand them over.  :)

RJ-12C and RJ-12W  -  These jacks are normally associated with one line of a key telephone system.  The RJ-12C is surface or flush mounted for use with desk telephone sets while the RJ-12W is for wallmounted telephone sets.  Typically, these arrangements are used when registered ancillary equipment must respond to central office or PBX ringing.

A+,N+,S+,L+,I+,HTI+,CET,CST,CNST,CNCT,CFOT,CCNT,ACSP,ISA CCST3

Just to clarify.....

RJ-11 is a 6P2C connection, in other words: 6 Position, 2 Contact

RJ-12 is a 6P4C connection, in other words: 6 Position, 4 Contact, it does have specific applications for key systems when there are issues of electrical line compatibility with the tip and ring.

RJ-14 is also a 6P4C connection, in other words: 6 Position, 4 Contact

And just for the record...there is no such thing as a RJ-45 in the USOC book, it is a 8P8C connection.

Hope this helps for anyone that is confused.
This is not my opinion, just the facts from the USOC book. :)