What headset can you use with a Cisco 7920 or 7921 cordless phone?

There is a 2.5mm headset jack on the Cisco 7920 and Cisco 7921 cordless phones, however, you may have already discovered that it is not a standard 2.5mm jack. Surprise! Why do they do this sort of thing? Is it just to drive people crazy? Perhaps. But fret not, we have the answer. The standard 2.5mm plug has 2 black bands on it. The non-standard 2.5mm plug has 3 black bands and that's what you need in order to make all the necessary connections inside the jack. You need any Plantronics H-series headet along with a special connector cable Plantronics part #65287-01 and that's all there is to it. Plug and play. Here's the link:

http://www.founderstelecom.com/heforci79coi.html