Single-line systems usually use just green and red. Christmas colors.
If you trace the four wires back to the source does that help? Do you have another working phone jack in the house? Check the wiring on that.
Hate to say it, but touch one wire to the phone's green, then one at a time, touch the other three wires to the red. Check each time for a dial tone.
Of no luck, touch the next of the four unknowns to the phone's green, then the other three to the red.
You should eventually find the pair that works.
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