ITT YEA-EXP38 Yealink IP Phone Expansion Module 38 programmable keys each with a dual-color LED. Daisy-chain 6 modules for 228 programmable keys. Supports Busy Lamp Field(BLF)&#44; Bridge Line Appearance(BLA). Programmable for speed dialing&#44; call pickup&#44; Intercom&#44;hold&#44; transfer&#44; voicemail&#44;