Cisco 7925G Administration Guide

Note
1
Tx power: Adjusts dynamically when associating with an AP if the AP client setting is enabled.
2
Data rate: Advertised rates by the APs are used. If the Restricted Data Rates functionality is enabled
in the Cisco Unified Communications Manager Administration phone configuration, then the Traffic
Stream Rate Set IE (Cisco Compatible Extensions [CCX] V4) is used.
Wireless Modulation Technologies
Wireless communications use the following modulation technologies for signaling:
Direct-Sequence Spread Spectrum (DSSS)
Prevents interference by spreading the signal over the frequency range or bandwidth. DSSS technology
multiplexes chunks of data over several frequencies so that multiple devices can communicate without
interference. Each device has a special code that identifies the data packets for the device and all other
data packets are ignored. Cisco wireless 802.11b/g products use DSSS technology to support multiple
devices on the WLAN.
Orthogonal Frequency Division Multiplexing (OFDM)
Transmits signals by using RF. OFDM is a physical-layer encoding technology that breaks one high-speed
data carrier into several lower-speed carriers to transmit in parallel across the RF spectrum. When used
with 802.11g and 802.11a, OFDM can support data rates as high as 54 Mbps.
The following table provides a comparison of data rates, number of channels, and modulation technologies
by standard.
Table 8: Data Rates, Number of Channels, and Modulation Technologies by IEEE Standard
802.11a802.11g802.11bItem
6, 9, 12, 18, 24, 36, 48,
54 Mbps
6, 9, 12, 18, 24, 36, 48,
54 Mbps
1, 2, 5.5, 11 MbpsData rates
Up to 2333 (Japan uses 4)Nonoverlapping
channels
OFDMOFDMDSSSWireless modulation
AP, Channel, and Domain Relationships
APs transmit and receive RF signals over channels within the 2.4 GHz or 5 GHz frequency band. To provide
a stable wireless environment and reduce channel interference, you must specify nonoverlapping channels
for each AP. The recommended 2.4 GHz channels to be used are 1, 6, and 11.
Regulatory domains determine the number of channels that wireless communications can use within the
frequency band. Radio Frequency Ranges, on page 25 list the frequency ranges, operating channels, and
Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G Administration Guide
29
VoIP Wireless Network
Wireless Modulation Technologies

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