This modular adapter has a DB9 male connector that plugs into DB9 RS232 serial port and converts it to an RJ11 or RJ12 connection.
RJ12 Pinout:
Pin1 -- White
Pin2 -- Black
Pin3 -- Red
Pin4 -- Green
Pin5 -- Yellow
Pin6 -- Blue
* Gold plated pin
* 26AWG wire
* Molded ivory color housing
* Thumb screw