This was the first type of two-line phone that didn't require a heavy cable and a closet full of equipment.
A knob on the front lets you select line #1 or line #2, and if you pull up the left-hand hookswitch plunger, you can hold the caller on one line while you switch to the other line. If you don't have two lines, you can use this as a one-line phone with hold. Built-in mechanical ringer, connected to line #1. "New Old Stock." Plastic is slightly yellowed from aging. ONE YEAR WARRANTY.