Apresa records calls from the Avaya (Nortel) CS1000 using passive recording. Passive recording means that Apresa is not an active participant of the call. During the call, VoIP data is routed through a network switch. The network switch sends a copy of the VoIP data to the Apresa using port-mirroring. Internal passive recording is done between the PBX and the phones. With this setup, Apresa records internal and external calls.
Avaya CS1000 uses the Unistim protocol.