Cisco 7925G Administration Guide

Voice Quality Metrics
To use the metrics for monitoring voice quality, note the typical scores under normal conditions of zero packet
loss and use the metrics as a baseline for comparison.
It is important to distinguish significant changes from random changes in metrics. Significant changes are
scores that change about 0.2 MOS or greater and persist in calls that last longer than 30 seconds. Conceal
Ratio changes should indicate greater than 3 percent frame loss.
MOS LQK scores can vary based on the codec that the phone uses. The following codecs provide these MOS
LQK scores under normal conditions with zero frame loss:
•
G.711 and G.722 codecs have maximum scores of 4.5
•
G.729A/AB codec has a maximum score of 3.8
A Conceal Ratio of zero indicates that the IP network is delivering frames and packets on time with no loss.
Voice Quality Troubleshooting Tips
When you observe significant and persistent changes to metrics, use the following table for general
troubleshooting information.
Table 49: Changes to Voice Quality Metrics
ConditionMetric change
Network impairment from packet loss or high jitter:
•
Average MOS LQK decreases could indicate widespread and
uniform impairment.
•
Individual MOS LQK decreases indicate bursty impairment.
Cross-check with Conceal Ratio and Conceal Seconds for evidence of
packet loss and jitter.
MOS LQK scores decrease
significantly
•
Check to see if the phone is using a different codec than expected
(Sender Codec and Rcvr Codec).
•
Check to see if the MOS LQK version changed after a firmware
upgrade.
MOS LQK scores decrease
significantly
•
Network impairment from packet loss or high jitter.
Conceal Ratio and Conceal
Seconds increase significantly
Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G Administration Guide
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Troubleshooting
Voice Quality Metrics

Cisco 7925G Specifications

General

Keypad number of keys	12
Display diagonal	2 \
Display resolution	176 x 220 pixels
Call waiting	Yes
Lines quantity	6 lines
Voice codecs	G.711a, G.722, G.729a, iLBC
Security algorithms	128-bit WEP, SSL/TLS, WPA
Supported network protocols	DHCP, TFTP, DNS, SCCP, SRST
Input voltage	100 - 240 V
Dimensions (WxDxH)	52 x 20 x 127 mm
Minimum system requirements	Cisco Unified Communications Manager 4.1, 4.2, 4.3, 5.1, 6.0, 6.1, 7.0 + Cisco Unified Communications Manager Express 4.3 +
Input frequency	50/60 Hz
Storage temperature (T-T)	-30 - 60 °C
Operating temperature (T-T)	0 - 40 °C
Operating relative humidity (H-H)	10 - 95 %
Product type	IP Phone
Product color	Gray
Safety	UL 60950, CSA 22.2 No.60950, EN 60950, IEC 60950, AS/NZS 60950, IEC 60529 (IP 54)
Certification	47 CFR 15 B ICES-003 B EN 55022 B AS/NZS CISPR 22 B CISPR 22 B VCCI B EN 61000-3-2 EN 61000-3-3 KN 22 EN 55024 EN 50082-1 EN 61000-6-1 EN 300386 EN 60601-1-2 KN
Compliance industry standards	IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.1X, IEEE 802.11e

Weight and Dimensions

Weight	138 g