Cisco 7940G Руководство по эксплуатации телефона - Страница 13

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.

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 screened 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 screened cables for the external device, or use cables with a better screen and connector.

–

Shorten the length of the external device cable.

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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].