MANUAL TEST FUNCTIONS
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Usage of the VoIP Test Adapter brings with it items that need to be noted:
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When using a PoE phone, if a specific VoIP Phone is suspected of sending audio data
when it is on-hook, then installing the VoIP Test Adapter will remove power from the
phone, which will interrupt the audio transfer in process, and possibly disconnect the
session, thereby alerting the intruder. For this case, if the phone is connected to a
managed switch, and you have the capability to configure port mirroring to an unused
port on that switch, this will not interrupt the audio transfer in process. Port Mirroring,
also known as SPAN (Switched Port ANalyzer), is a method of monitoring all network
traffic seen on one (or more) port(s) (the Monitored port), to another port (the Analysis
port). This is visualized in the following figure:
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This same “Mirrored Port” method can be used with VoIP Phones not using PoE or even
on PCs to see if they are passing audio using programs such as Skype.
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If the VoIP Phone is not using PoE, but has an external power supply, and it is in the
processing of sending audio, meaning, a connection is made and someone is “listening”
from another phone, then it is possible, with practice to connect the VoIP Test Adapter
and not lose the connection nor the audio transfer. This requires that the VoIP Test
Adapter already have one of the short CAT5 cables connected on the Network side of
the VoIP Test Adapter, and quickly remove the VoIP Phone’s cable from the router/wall,
and plug it into the Phone side of the VoIP Test Adapter, then plug the VoIP Test
Adapter Network cable back into the same physical port on the router/wall. This is
relying on TCP to maintain the connection after a less than a second data loss.
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Whereas it is possible to monitor more than one port via Port Mirroring (e.g. mirror
both VoIP Phones and the PC shown above), one should keep performance in mind. If
you mirror traffic from multiple ports, the mirrored traffic may exceed the capacity of
the TALAN. To help reduce the possibility of dropping packets in the TALAN, it is possible
to set up packet filters in the TALAN, see VoIP Plus+ for more information on how to
set/adjust Receive Filters.
