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.
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, 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.
In European Union countries, use only external speakers, microphones, and headsets that are fully compliant with the EMC Directive [89/336/EC].
Cisco Product Security Overview
This product contains cryptographic features and is subject to
United States and local country laws governing import, export, transfer, and
use. Delivery of Cisco cryptographic products does not imply third-party
authority to import, export, distribute, or use encryption. Importers,
exporters, distributors, and users are responsible for compliance with U.S. and
local country laws. By using this product you agree to comply with applicable
laws and regulations. If you are unable to comply with U.S. and local laws,
return this product immediately.