The previous pin outs MAY work. However the RJ12 Serial Bus on the 1220 is missing a key signal pin and may not work. If you find yourself still struggling, switch to a USB modem. Remember, a USB will translate to a Com Port # in Windows (just don't plug in it in to another USB Port or it will create a new Com Port #!) USe the Com port # assigned to do what you need a conventional serial port ID.
Good Luck.