These are some of the limitations of the Silent Monitor feature:
A supervisor must log on to a hardphone when the Silent Monitor is used through the IPCC Supervisor Softphone. These Cisco IP phones are supported for use with Silent Monitor:
The IP phone agents cannot be Silent Monitored. Agents need to be logged on to a supported hardphone, with the Agent desktop PC connected to the second port of the phone, or through Media Termination. Refer to Cisco ICM Software CTI OS System Manager's Guide for more information.
There is no hard limit for concurrent Silent Monitor sessions. But, the maximum number of concurrent Silent Monitor sessions can be limited by the number of agents and supervisors, as well as the networks ability to handle the additional network traffic.
If agents use IP hard phones, they need to be left in the default configuration, where voice traffic is replicated on the second port.
These are the supported audio codecs for the Silent Monitor feature:
If a USB digital headset is unplugged from the USB port during a Silent Monitor session and then plugged back in, the IPCC Supervisor Desktop application can freeze. Use an analog headset if the environment sometimes requires that the headset be unplugged while an agent is monitored on a call.
Additionally, Silent Monitor does not work with all NICs.
If agents use supported IP hardphones with their desktops connected to the second port of the phone, and if the network is configured to use a VLAN for voice traffic, the network card and driver in the agent desktop PC must be able to capture packets on a different VLAN in order for Silent Monitor to work. This restriction does not apply if the network is not configured for VLANs. Cisco tests have determined that several NICs manufactured by Intel are not capable of packet captures from a different VLAN. No workaround exists for the Intel Pro/1000 and the Intel 8255x-based PCI Ethernet Adapter cards.
For NICs from other manufacturers, there are procedures in order to determine if the NIC can capture packets on a different VLAN.