Cisco 8821 Administration Manual page 146

Technical Specifications
Headset Usage
Cisco recommends the use of good quality external devices, like 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 cell phones and two-way radios, some audio noise may still occur.
The primary reason that a particular headset would be inappropriate for the phone is the potential for an audible
hum. This hum can be heard by either the remote party or by both the remote party and the phone user. Some
humming or buzzing sounds can be caused by a range of outside sources; for example, electric lights, being
near electric motors or large PC monitors. In some instances, the mechanics or electronics of various headsets
can cause remote parties to hear an echo of their own voice when they speak to phone users.
Related Topics
External Devices
Cisco Wireless IP Phone 8821 and 8821-EX Administration Guide for Cisco Unified Communications Manager
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