The SIP Print call recording appliance “listens” for VoIP traffic on the network. In order for it to hear all VoIP activity, including internal station-to-station activity, that traffic must be mirrored to the appliance via a port-mirroring switch.
A typical network switch segments traffic by IP address (some use MAC ID’s as well). Switches gained favor over hubs because they reduced network traffic. Hubs simply acted like local repeaters, broadcasting all traffic throughout the network and creating a lot of excess network load.
A port-mirroring switch acts just like a normal switch, with the additional capability of making a copy of traffic from and to one or many ports and sending that replicated traffic to an additional port. Once properly configured, a port-mirroring switch can copy (mirror) all traffic to and from any specified switch ports and send that mirrored traffic to the port connected to the call recording appliance. Now the appliance will receive a copy of the traffic to/from any handset, including internal station-to-station calls, and can record conversations.
In cases where a SIP trunk is connected to the IP-PBX (the SIP proxy) or to a gateway/router or other network device (including PSTN translators) connected to the port mirroring switch, traffic to and from this port should be mirrored to the port connected to the call recording appliance.
This might be considered excessive, but in this manner all traffic to and from the handsets and the PSTN is captured and recorded while eliminating duplicate VoIP packets.
There are three common scenarios for configuring a SIP Print call recording system in a VoIP network environment. The choice is made based on your network geometry and the types of telephone conversations you intend to record.
Capture calls to and from outside the VoIP network (known as trunk side – you must have SIP trunks to do this), but do not capture local handset to local handset calls.
Capture calls from handset to handset, and to and from outside the VoIP network as well. All ports on the port-mirroring switch mirror to the SIP Print port (which is not a mirrored port).