Avaya EU24 Key Expansion Module - #700381817
A single EU24 is supported on the following phones - 2420/5420, 4620/5620, 4621/5621, and 4625. It requires an Avaya 1151 series power supply for digital telephones. For IP phones, use of PoE is supported if the PoE is Class Three. IP Office supports a maximum of eight EU24s on each IP Office system.