Cisco 9971 - Mute; On-Hook Dialling; Dialing Numbers On-Hook and Internationally; Redial

Network Bandwidth
When using secure video over VPN and VXC/VPN, the maximum supported bandwidth is 320 kpbs.
When the phone calls Cisco TelePresence, the maximum bandwidth is 320 kbps.
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 Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager 10.0
19
Network Bandwidth