In article ,
Mark Lloyd wrote:
On Sun, 24 Dec 2006 22:23:08 -0600, "rb" wrote:

Are RJ11 and RJ14 modular plugs the same size?

Do they physically fit the same jack?

The RJ14 jack can accommodate six conductors. If you use a single line,
four conductor phone cord (assumes a four conductor plug) into an RJ14 jack,
does it work OK (assumes the device the jack is in is a single line phone?

Will a two line, four conductor phone cord (assumes a four conductor plug)
work OK in an RJ14 jack (assumes the device the jack is in is a two line
phone)?


Probably.

I see the 6P6C (6-conductor) jacks called RJ12. Those are the same
size as 6P4C ones (RJ11). A RJ11 plug will fit into a RJ12 jack, with
the 4 conductors automatically making contact with pins 2-5. An RJ12
plug will work, except than pins 1 & 6 will not be connected. An RJ12
crimping tool will work on RJ11 plugs (I think) but an RJ11 crimping
tool will NOT work on RJ12 plugs.


None of the modular plugs have an RJ designation until they are wired
for a specific telephone application.

All 6 position jacks are the same physical size, the number of contacts
determine which applications it can be wired for.

For RJ11, the minimum is 2 contacts.
For RJ12, RJ13, and RJ14, the minimum is 4 contacts.
For RJ25, the minimum is 6 contacts.

RJ11 is used for a single line, pins 3/4.
RJ14 is used for two lines, pins 3/4, and 2/5.
RJ25 is used for three lines, pins 3/4, 2/5, and 1/6.

RJ12 and RJ13 are used for a single line, pins 3/4, with A-lead control
pins 2/5.

RJ12 and RJ13 are not commonly seen, as the 1A2 key systems that they
were used with are largely extinct. Both RJ12 and RJ13 use the second pair
(pins 2/5) for the A lead control, which conflicts with RJ14, which
uses that pair for the second line. A device wired for RJ12 or RJ13 will
short the second line when plugged into a jack wired RJ14.

The difference between RJ12 and RJ13 is that RJ12 bridges the line before
the key system, and RJ13 bridges the line after the key system.


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