Please Note: The model number of your Linksys telephone (also known as Cisco Small Business IP Phone) can usually be found on a label stuck on the bottom of the phone.
These phones have a dedicated 2.5mm headset port. Non-mainstream headsets will require an RJ to 2.5mm adaptor cable.
Plantronics corded:
Any HW series headset with a Quick Disconnect to 2.5mm Vista bottom cable.
Jabra/Netcom corded:
Any headset top and a standard cable with a 2.5mm plug.
Sennheiser corded:
Any headset top and a CCEL 191-2 cable.