Solved: 8800 Series Audio KEM, 28 Button not working on 8861 Phone - Cisco Community
Cisco 8865 Key Expansion Module (CP-8800-V-KEM=)
Cisco - CP-8800-A-KEM= - 8800 Series Audio KEM, 28 Button
Cisco IP Phone 7800 and 8800 Series Accessories Guide for Cisco Unified Communications Manager - Key Expansion Modules [Cisco IP Phone 7800 Series] - Cisco