RJ-12?

[rpearson]

I have recieved a request by a customer to construct a patch cable consisting of RJ-12 mod plugs on each end per spec.In all my years in this field I have never came accross the term RJ-12(aside from the usual RJ stuff).The spec sheet (Cisco) tels me this will be a 6P6C utlizing only 3 of the pins.Now my assumption is this is going to be a standard RJ-11(telephone)with 6P6C in place,and the term"RJ-12" is just a technical description of the mod plug.Please iterate.Thanks.

 

[OldPhoneGuy]

RJ12 is a telephone/LAN wiring standard that consists of 6-wire cable and connectors. RJ12 components consist of 6-wire telephone cable, 6-wire male plugs and 6-wire female jacks.

 

[Bobg1]

Where as rj11 is only 4 wire.
But yes physically they are the same size.

 

[rpearson]

Thanks all.

 

[Nyg]

Sorry to correct people but RJ-11 and RJ-12 are not the same size, they are both 4 pin but the RJ-11 is larger than the RJ-12.

The RJ-11 is usually a phone conector.

The RJ-12 is usually a phone handset connector.

 

[daronwilson]

Not so sure that I agree, I have this for reference information from the BICSI TDDM:

The third letter of the RJ designation indicates the jack category:

RJ1: 6 position jack

RJ2: 50 position bridgin ribbon jack

RJ3: 8 position series jack

RJ4: 8 position data jack

RJ6: 8 position jack

RJ7: 50 position series ribbon jack

If this is true, the RJ12 would be on a 6 position jack. Often the 6 position jacks/plugs are made with only 4 pins, but the width and size of the plug is the same.

Handset connectors are only 4 pin (not 6 position) and physically a smaller size of plug. If you have some reference showing otherwise, please share it so I can clear this up in my mind.

thanks!

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[franklin97355]

Daron's right on this one (Not to suggest that he is sometimes wrong)

 

[BOKA]

Agree with DARONWILSON and just want to add that connector between headset and the phone base is RJ9.

 

[Nyg]

To Daron

The refernce I used is COMPTIA A+

If you use SYBEX Complete A+ second Edition (UK) (ISBN 0-7821-2802-5)on page 18 it clearly states:

RJ-11, 4 pin, Male, Telephone wall jack phone cord

RJ-12, 4 pin, Male, Telephone Handset cord.

 

[franklin97355]

According to the FCC reg that originally defined the RJ system there are no RJ designations for 4 position plugs. There also is no RJ12. RJ11 is a single line jack/plug with the center two pins designated as tip and ring. RJ14 is a two line jack/plug. Maybe AT&T or someone else has set up these designations but I can't find them in the FCC or USOC codes.

 

[daronwilson]

Interesting, I don't know what comptia is, but it seems they have their information incorrect. I have to agree with franklin97355, as this information agrees with my reference material. I'll keep looking, but I suspect comptia is in error.

Thanks!

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[daronwilson]

The interesting thing to remember is that the RJ designator is a method of wiring, not a device. I think the Universal Service Order Code (USOC) was originally put together by AT&T to instruct their personnel how to terminate services, and on what type of connection. Later the FCC approved several of the interfaces so that there were connection and dmarc terms that that were universal as the breakup of the bell system brought lots of connectivity to formally regulated technologies. Technically you cannot buy an RJ-11. You CAN wire a 6position4pin plug or jack to be an RJ-11 connection.

The comptia reference sounds like it is telling you that an RJ-11 is a "4 pin, Male, Telephone wall jack phone cord", but the wall or surface jack you plug that cord into can also be wired as an RJ-11.

I cannot find a specific definition of the RJ-12 USOC wiring code. People seem to be using it to mean a 6position6conductor connection. There is quite a bit of mis-use of the terminology, so many people refer to anyting with an 8 pin plug or jack as an RJ45, when 8 pin connections can be RJ-45, RJ48, etc.

Curious, what Cisco gear was it and what is the connection for specifically? Not sure why they would want 3 wires in the 6 pin jack.

Good Luck!


It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[rpearson]

The patch cable and modular plug in question was utilized for configuration of some Cisco equipment.Mainly,from an adapter on the laptop,to a NIC or other network adapter within the equipment,enabling configuration of the device.Based on the Cisco documentation,pins 2,3,5(Tx,Rx,GND-Straight Through),unknown as to why this had to be a 6P6C mod plug.The other pins were to be left open.Cisco stated this to be an RJ-12.Ive never ran into this term in the 10+ years I been in the field,and its clear to me that its not the physical size of the plug that makes it become RJ-11,RJ-12,etc.Is this correct?Or am I still confused?I whipped the cable up for them,and they were on there way.

 

[daronwilson]

Interesting, so it is a serial cable. Well who knows what they really wanted, but I'd bet my lunch money that a 3 wire connection on a 6 pin plug is not an RJ12 in ANYONE's book but theirs.

See my earlier post about the first number after RJ determining what size of jack or plug it is.

Thanks for sharing, that is definately an interesting one I've not encountered either.

Good Luck!

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[ANFPS26]

That reminds me of ADT, the alarm company. They wanted me to put in a phone jack for our alarm system where I used to work. The ADT installer gave me a part number that the phone jack had to be. I had never heard of one and neither had my co-workers. I put in a standard RJ-11 two line jack and the guy was happy. He was just reading off his work order. He never knew the difference.

Jim

 

[daronwilson]

The importance regarding the alarm system is that it MUST be as an RJ31X to function properly. The RJ31X has the line coming in on one pair, and then out to the rest of the building on another pair. This is essential because in a burglarly situation, the alarm panel seizes the line, places it on hook momentarily if it was in use, draws dialtone, and then calls the monitoring service. The important thing it does is disconnect the phones in the building. If this is NOT wired this way, the bad guy can come in, pick up any phone, and disrupt the call out to the alarm company.

If it is a fire alarm system, they are required two lines for monitoring and the panel looks at the voltage on each line, reporting a trouble if either line goes out. This is pretty important.

When I do an alarm system, I go directly to the building interface (MPOP) and make the connection there, sending a dial tone to my alarm panel and the getting it back to distribute it everywhere else. I find that many phone guys don't understand this part, and it means a return call for me or worse yet, failure for the system to function in the event of an alarm.

Almost ANY alarm system that dials out will require an RJ31x connection (either a jack and pigtail OR hardwired in the alarm panel) so that the alarm system can dial and exclude all the other phones.

We routinely run a Cat5e of a different color from the alarm panel to the MPOP, and make the connections without a jack, this helps to keep the employee from disabling the call out part of the alarm system.

Good Luck!


It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[ANFPS26]

In this case we supplied our own dialtone and the lines were dedicated and not on the office phones. We were a CLEC and had our own switch. I see what you are saying if it used the office line to dial out.

Jim

 

[daronwilson]

Point well taken, dedicated lines obviously would not need to return anywhere, thanks for pointing that out.



It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[jacassc]

hmmmmm....wonder how ADT's 8 position plugs where able to fit in 6 position jacks..lol
also wonders how many ppl refer to 8pos/8contact jacks and patch panels as..RJ 45's..lmfao

 

[ANFPS26]

This alarm system used two telephone numbers on separate jacks. No RJ-45 plug, just two RJ-11 plugs. He got it to work and never questioned anything. All we did was supply him dialtone.

Jim