Cisco 521 Wired Single Ear USB Headset (CP-HS-W-521-USB=) - VoIP Supply
Amazon.com: CISCO Headset 561, Wireless Single On-Ear Digital Enhanced Cordless Telecommunications Headset with Standard Base for US & Canada, Charcoal, 1-Year Limited Liability Warranty (CP-HS-WL-561-S-US=) : Electronics
Cisco Headset Compatibility Guide: Everything You Need To Know