Originally Posted by Uranium-235
I thought RJ31 was physically compatible with Cat5
If it is a true RJ31x then there are shorting pins between 1 and 4, 5 and 8. With no connections for 2, 3, 6 or 7.

Telco in on terminals 4, 5 and out on 1, 8.

What does the wiring of the actual jack look like?

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