Normally, on a 4-wire circuit, the "word doc" (may be called differently where you are) will specify which pair is transmit and which one is receive.

All you have to do is wire them accordingly.

As previously stated, T&R is one side of the circuit (tip and ring) while T1&R1 is the other.

Even if you were to reverse them, it can still be corrected in the field - been there and done that many a times - so it's not the end of the world.

"...Time moves slowly and it goes so fast..."

(Sandy Denny)