But of course!
The Plantronics Mute Switch NOW DISCONTINUED (Cat# 1640) works just fine with Leitner corded headsets. So, if you’d like your LH240 or LH245 QD headsets to have mute capabilities, then the Plantronics Mute Switch is your best friend!
PS: This goes between the headset and the quick disconnect cord. To use, just push the big red button. Super easy!