The Avaya IP Office 500 version 2 Control Unit is the most suitable of the IP Office range for IP Telephony applications. It also provides an entry level offer into the IP Office family through IP Office Standard Edition software. The IP Office 500 is a stackable unit with an optional 19 rack mounting kit (700429202) and an optional wall mounting kit (700430150) for smaller configurations. Avaya IP500 System unit has a number of features, see below. The IP Office 500 system supports up to 272 telephones, with capacity for 16 analogue trunks or 4 digital trunks.