DB9 Male / RJ12 Female, Gray.
This unit allows you to configure your own specific pinouts. When trying to run a serial connection over a very long distance, it is better to use a phone line to do so. It will cut down on signal loss and interference.
RJ12 Pin Outs: 1-White, 2-Black, 3-Red, 4-Green, 5-Yellow, and 6-Blue.