To add a line monitor to a windstream phone:

Open the Windstream portal, then navigate to the extensions manager

click the edit pen for the extension you wish to modify

Scroll down to the Call Monitor Group and click the edit gear

Select the extensions you want to monitor via your phone - then click save

Now select the Program Phone Keys edit gear - a new window will openĀ 

Select the button you wish to modify

Select Monitor Phone

Now enter the label to display on the phone and select the extension you wish to monitor, then click save.

You should now see the monitor on the phone display.