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5.9.
Configuration of VOIP telephony recording
In all the telecom networks described so far, the TAP connections are all based on the same principle of
"high impedance signal tapping". With modern telephony based on Ethernet, like VoIP, the actual
tapping job is not on the hardware level, but on the TCP/IP packet level. The "packet tapping" is
performed by a port-mirroring switch.
Port mirroring functionality is supported by almost all enterprise-class network switches, also called
managed switches. On Cisco switches, the port-mirroring functionality is referred as 'SPAN or RSPAN'.
A VoIP network that requires call recording must always deploy at least one port-mirroring switch. This
switch must be configured to copy packets from one or more (source) ports to one (destination) port.
The destination port is normally connected to the recorder system and the destination port of the switch
actually forms a single or multiple-TAP.
Another important issue to consider regarding the switch selection is the internal bandwidth of this
device. This is an issue that requires the assistance of the network manager at the customer premises,
especially with topologies where data and VoIP are sharing the Ethernet. The switch that we supply has
an internal bandwidth of 32 Gbps.
With VoIP telephony, all information is sent over the network by (RTP / SIP etc.) packets. The basic
issue of the whole configuration job of VoIP telephony recording is to setup the network components in
such a way that the APRESA 'see' these RTP packets on its recording NIC (NIC, Network Interface
Card).
Apresa uses RTP data to record the audio of VoIP calls. The VoIP PBX should be configured to use
only G.711, G.722, G.729, GSM 6.10, or iLBC. These Codecs are supported in Apresa. Apresa will not
record audio in other Codecs. Some VoIP telephones can also be configured for Codecs.
For every APRESA recording channel that uses the G.729 codec an additional G.729 license must be
purchased besides the channel license.
It is also required by the APRESA that the encryption on the VoIP PBX is switched off.
Depending on the customers recording requirements we distinguish 2 fundamental different
solutions 1) Trunk Side Recording and 2) Station Side Recording
5.9.1.
Trunk Side Recording
This method will record inbound and outbound calls. The internal (or local) calls however are NOT
recorded. With trunk side recording, only one port-mirroring switch is needed to facilitate a single tap on
the VoIP PBX. The simple switches (without port-mirroring) that may be used in the existing VoIP
network need not to be replaced.
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INSTALLATION MANUAL APRESA
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