The transmit and receive volume levels of the individual CO line ports of the X16 can be manually adjusted. This is a complicated process that can lead to an undesirable outcome. We recommend that you write down the starting settings before making changes. This will allow you to return to the original settings, if needed. Adjustment Procedure:

• Press Program and then Dial * # 600618 * #
• Press Enter twice (Enter is the center button next to the display)
• Use Up and Down next the display to scroll to KSU HiddenPgm, then press Enter
• Scroll to CO Tx / Rx Gain, then press Enter

(Note that Tx is transmit level and Rx is receive level)

• Scroll to the specific CO Tx or Rx to change, then press Enter
• Scroll up or down to change the volume level, then press Enter

Repeat Steps 5 and 6 for each CO Tx or Rx you wish to change.