Avaya IP Office 400 is a flexible business communications system targeted at small businesses. Depending on the size of customer, Avaya offers a range of IP Office system processors to provide an economical and scalable solution.

It was officially retired in May 2008 and replaced by the IP Office 500.

IP Office 400 Control Hardware

IP400 Control Units
IP400 External Expansion Modules
IP400 Trunk Interface Cards
IP400 Voice Compression Modules (VCM)