Cisco 7821 Administration Guide

Sometimes, use of a local power cube or power injector may reduce or eliminate hum.
Note
Environmental and hardware inconsistencies in the locations where Cisco IP Phones are deployed mean that
no single headset solution is optimal for all environments.
We recommend that customers test headsets in the intended environment to determine performance before
making a purchasing decision to deploy on a large scale.
You can use only one headset at a time. The most-recently connected headset is the active headset.
Audio Quality
Beyond physical, mechanical, and technical performance, the audio portion of a headset must sound good to
the user and to the party on the far end. Sound quality is subjective, and we cannot guarantee the performance
of any headsets. However, various headsets from leading headset manufacturers are reported to perform well
with Cisco IP Phones.
For additional information, see https://www.cisco.com/c/en/us/products/unified-communications/uc_endpoints_
accessories.html
Analog Headsets
Analog headsets are supported on the Cisco IP Phone 7821, 7841, and 7861. The Cisco IP Phone 7821, 7841,
and 7861 can detect when an analog headset is plugged in.
Cisco IP Phone 7800 Series Multiplatform Phones Administration Guide
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Hardware and Accessory Installation
Audio Quality

Cisco 7821 Specifications

General

Brand	Cisco
Model	7821
Category	IP Phone
Language	English