Cisco 7940G - IP Phone VoIP Manual page 11

Phone guide
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Using an External Power Supply
The following warnings apply when you use the external power supply with the Cisco IP Phone:
Warning
This product relies on the building's installation for short-circuit (over current)
protection. Ensure that a fuse or circuit breaker no larger than 120 VAC, 15A U.S. (240 VAC,
10A international) is used on the phase conductors (all current-carrying conductors).
Warning
The device is designed to work with TN power systems.
Warning
The plug-socket combination must be accessible at all times because it serves as the
main disconnecting device.
Only use the Cisco specified power supply with this product.
Caution
Using External Devices with Your Cisco IP Phone
The following information applies when you use external devices with the Cisco IP Phone:
Cisco recommends the use of good quality external devices (speakers, microphones, and headsets) that
are shielded against unwanted radio frequency (RF) and audio frequency (AF) signals.
Depending on the quality of these devices and their proximity to other devices such as mobile phones
or two-way radios, some audio noise may still occur. In these cases, Cisco recommends that you take
one or more of the following actions:
• Move the external device away from the source of the RF or AF signals.
• Route the external device cables away from the source of the RF or AF signals.
• Use shielded cables for the external device, or use cables with a better shield and connector.
• Shorten the length of the external device cable.
• Apply ferrites or other such devices on the cables for the external device.
Cisco cannot guarantee the performance of the system because Cisco has no control over the quality
of external devices, cables, and connectors. The system will perform adequately when suitable devices
are attached using good quality cables and connectors.
In European Union countries, use only external speakers, microphones, and headsets that
Caution
are fully compliant with the EMC Directive [89/336/EC].
Cisco IP Phone 7960G and 7940G
Getting Started
3

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