I2T Serial Port Adapter
From ATTWiki
The I2T serial port is an RJ45 receptacle with this pinout:
(This pinout is from http://www.toolboxopc.com/Support/More_Downloads/Airlink-Modbus/airlink-modbus.html)
This is an image of an RJ45 to DB9 adapter with the above wiring. The DB9 port is female to attach to a standard PC male port.