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Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager 8.5 (SIP)
OL-20861-01
Chapter 3 Setting Up the Cisco Unified IP Phone
Understanding the Cisco Unified IP Phone Components
USB Port Data Information
The Cisco Unified IP Phone supports a maximum of five devices connected to each USB port. Each
device connected to the phone is included in the maximum device count. For example, your phone can
support five USB devices (such as three Cisco Unified IP Color Key Expansion modules, one hub, and
one other standard USB device) on the side port and five additional standard USB devices on the back
port (the Cisco Unified IP Phone 8961 does not have a back USB port). (Many third-party USB products
count as several USB devices, so refer to documentation that came with a third-party product.)
Note Unpowered hubs are not supported, and powered hubs with more than four ports are not supported.
Note USB headsets connected to the phone through a USB hub are not supported.
The Cisco Unified Video Camera connected to the phone through a USB hub is not supported.
External Speakers and Microphone
External speakers and microphones are plug-and-play accessories. You can connect an external PC-type
microphone and powered speakers (with amplifier) on the Cisco Unified IP Phone 9951 or 9971 using
the line in/out jacks. Connecting an external microphone disables the internal microphone and
connecting an external speaker will disable the phone’s internal speaker.
Note Using poor quality external audio devices, playing loudspeakers at very loud volumes or placing the
microphone very close to the loudspeaker may result in undesirable echo heard by other parties on your
speakerphone calls.
Headsets
Although Cisco Systems performs internal testing of third-party headsets for use with the Cisco Unified
IP Phones, Cisco does not certify or support products from headset or handset vendors.
The phone reduces some background noise that is detected by a headset microphone, but if you want to
further reduce the background noise and improve the overall audio quality, use a noise cancelling
headset.
Cisco recommends the use of good quality external devices, for example, headsets that are screened
against unwanted radio frequency (RF) and audio frequency (AF) signals. Depending on the quality of
headsets and their proximity to other devices such as mobile (cell) phones and two-way radios, some
audio noise or echo may still occur. An audible hum or buzz may be heard by either the remote party or
by both the remote party and the Cisco Unified IP Phone user. Humming or buzzing sounds can be
caused by a range of outside sources; for example, electric lights, electric motors, or large PC monitors.
See Using External Devices, page 3-11, for more information.
Note In some cases, hum may be reduced or eliminated by using a local power cube or power injector.
These environmental and hardware inconsistencies in the locations where Cisco Unified IP Phones are
deployed means that there is not a single headset solution that is optimal for all environments.