RJ ... 'Registered Jack', telephone connection interfaces, registered with the FCC, the U.S. Federal Communications Commission. Their history goes back to the Bell System and AT&T's Universal Service Order Codes (USOC) in the 70s. These were adopted later as part of the FCC regulations.
Position |
telephone, data | |||||
Position |
standard telephone connection, data | |||||
Position |
telephone, data | |||||
Position |
connection for 2 analog phone lines | |||||
Position |
ISDN, LAN, data | |||||
Position |
DATA |
The RJ48 has an extra tab so that a RJ48 plug will not push into a RJ45 jack, but a RJ45 plug will mate with a RJ48 jack.
ISDN BRI RJ45 Standard | ||||||||||
RJ 45 Pin | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | ||
Pair | Tx+ | Rx + | Rx - | Tx - |