Cisco 7925G Administration Guide

Received Signal Strength Indicator (RSSI)
Signal strength of available APs within the RF coverage area. The phone attempts to associate with the
AP with the highest RSSI value.
Traffic Specification (TSpec)
Calculation of call limits and WLAN load balancing. The TSpec value of each voice stream allows the
system to allocate bandwidth to voice devices on a first-come, first-served basis.
The wireless IP phone associates with the AP with the highest RSSI and lowest channel usage values (QBSS)
that have matching SSID and encryption types. To ensure that voice traffic is handled properly, you must
configure the correct QoS in the AP. For configuration information, see Cisco Unified Wireless IP Phone
7925 and 7926 Series Deployment Guide.
Related Topics
Voice Communication Security in WLANs, on page 39
Site Survey Verification, on page 44
Voice QoS in Wireless Networks, on page 35
Voice QoS in Wireless Networks
Voice traffic on the Wireless LAN, like data traffic, is susceptible to delay, jitter, and packet loss. These issues
do not impact the data end user, but have serious implications for a voice call. To ensure that voice traffic
receives timely and reliable treatment with low delay and low jitter, you must use Quality of Service (QoS),
and use separate virtual LANs (VLANs) for voice and data. By isolating the voice traffic onto a separate
VLAN, you can use QoS to provide priority treatment for voice packets when traveling across the network.
Also, use a separate VLAN for data traffic, not the default native VLAN that is typically used for all network
devices.
You typically need at least three VLANs on the network switches and the APs that support voice connections
on the WLAN. These VLANs are:
Voice VLAN
Voice traffic to and from the wireless IP phone
Data VLAN
Data traffic to and from the wireless PC
Native VLAN
Data traffic to and from other wireless infrastructure devices
Assign an SSID to the voice VLAN and a different SSID to the data VLAN. If you configure a separate
management VLAN in the WLAN, do not associate an SSID with the management VLAN.
By separating the phones into a voice VLAN and marking voice packets with higher QoS, you can ensure
that voice traffic gets priority treatment over data traffic, resulting in lower packet delay and fewer lost packets.
Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G Administration Guide
35
VoIP Wireless Network
Voice QoS in Wireless Networks

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