The MCS-7815I-2.0-ECS1 is the model of the MCS-7815I-2000 designed for the Unity application. This model will support up to 499 voice messaging or unified messaging users. The MCS-7815I-2.0-ECS1 model also supports the Unity Bridge application, linking a Unity system to an Octel voice mail system and providing message interoperability between subscribers on the Unity messaging system and the Octel system.