Avaya IP500 V2 is a control unit which is an evolution of the existing IP500 and is fully backward compatible with it. IP500 V2 has 4 card slots into which all existing IP500 cards can be inserted, as well as several new cards which are introduced with Release 6. Moreover, Avaya IP500 V2 requires the presence of a system SD (Secure Digital) card to operate and to act as its feature key. Packed with all these features, this control unit operates in standard IP Office mode as well as a new Avaya IP Office Essential Edition Partner Version.