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E1 Pinout

This page tries to summarize various E1 line pin-outs.

Name RJ45 Digium RJ45 Auerswald Livingston PM3
RxN (ring) 1 1 1
RxP (tip) 2 2 2
TxN (ring) 4 4 4
TxP (tip) 5 5 5
UB- - 7 -
UB+ - 8 -

When connecting two E1 ports with another, the Rx pair always needs to be crossed over to the Tx pair of the other side. There is no feature like Auto-MDI-X in Ethernet!

E1 cross-over

See https://support.digium.com/community/s/article/How-do-I-make-a-T1-E1-Crossover-cable

A T1/E1 crossover cable has pin 1 routed to pin 4 and pin 2 routed to pin 5.

Pin 1 will be the far left pin when holding the plug with the lock-tab facing away from you. Pin 8 will then be the far right pin.

1 <-> 4
2 <-> 5

The other pairs of the cable should all be routed straight through (the T568A standard may be used as an example for this).

This is not compatible with an Ethernet cross-over cable which swaps 1<->3 and 2<-> 6 (and optionally 4 <->7 and 5 <-> 8).

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