Power Outage; External Devices; Phone Behavior During Times Of Network Congestion - Cisco 7906G User Manual

Preface

Power Outage

Your access to emergency service through the phone depends on the phone being powered. If there is a power
interruption, Service and Emergency Calling Service dialing will not function until power is restored. In case
of a power failure or disruption, you may need to reset or reconfigure the equipment before using the Service
or Emergency Calling Service dialing.

External Devices

Cisco recommends using good quality external devices such as headsets, cables, and connectors that are
shielded against unwanted radio frequency (RF) and audio frequency (AF) signals.
Not all Cisco IP Telephony products support external devices, cords or cables. For more information,
Note
consult the documentation for your phone.
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 these 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 external devices, cables, and connectors.
Caution In European Union countries, use only external speakers, microphones, and headsets that are fully compliant
with the EMC Directive [89/336/EC].

Phone Behavior During Times of Network Congestion

Anything that degrades network performance can affect Cisco IP Phone voice and video quality, and in some
cases, can cause a call to drop. Sources of network degradation can include, but are not limited to, the following
activities:
• Administrative tasks, such as an internal port scan or security scan
• Attacks that occur on your network, such as a Denial of Service attack
Cisco Unified IP Phones 7906G and 7911G User Guide for Cisco Unified Communications Manager 9.0 (SCCP and
Power Outage
SIP)
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