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Chapter 12 Interfaces
ISG50 User’s Guide
252
• You can set the 3G device to connect only to the home network, which is the network to which
you are originally subscribed.
• You can set the 3G device to connect to other networks if the signal strength of the home
network is too low or it is unavailable.
Aside from selecting the 3G network, the 3G card may also select an available 2.5G or 2.75G
network automatically. See the following table for a comparison between 2G, 2.5G, 2.75G and 3G
of wireless technologies.
To change your 3G WAN settings, click Configuration > Network > Interface > Cellular.
Note: Install (or connect) a compatible 3G USB to use a cellular connection.
Note: The WAN IP addresses of a ISG50 with multiple WAN interfaces must be on
different subnets.
Table 69 2G, 2.5G, 2.75G, 3G and 3.5G Wireless Technologies
NAME TYPE
MOBILE PHONE AND DATA STANDARDS
DATA
SPEED
GSM-BASED CDMA-BASED
2G Circuit-
switched
GSM (Global System for Mobile
Communications), Personal Handy-phone
System (PHS), etc.
Interim Standard 95 (IS-95), the first CDMA-
based digital cellular standard pioneered by
Qualcomm. The brand name for IS-95 is
cdmaOne. IS-95 is also known as TIA-EIA-95.
Slow
Fast
2.5G Packet-
switched
GPRS (General Packet Radio Services), High-
Speed Circuit-Switched Data (HSCSD), etc.
CDMA2000 is a hybrid 2.5G / 3G protocol of
mobile telecommunications standards that
use CDMA, a multiple access scheme for
digital radio.
CDMA2000 1xRTT (1 times Radio
Transmission Technology) is the core
CDMA2000 wireless air interface standard. It
is also known as 1x, 1xRTT, or IS-2000 and
considered to be a 2.5G or 2.75G technology.
2.75G Packet-
switched
Enhanced Data rates for GSM Evolution
(EDGE), Enhanced GPRS (EGPRS), etc.
3G Packet-
switched
UMTS (Universal Mobile Telecommunications
System), a third-generation (3G) wireless
standard defined in ITU
A
specification, is
sometimes marketed as 3GSM. The UMTS
uses GSM infrastructures and W-CDMA
(Wideband Code Division Multiple Access) as
the air interface.
CDMA2000 EV-DO (Evolution-Data Optimized,
originally 1x Evolution-Data Only), also
referred to as EV-DO, EVDO, or just EV, is an
evolution of CDMA2000 1xRTT and enables
high-speed wireless connectivity. It is also
denoted as IS-856 or High Data Rate (HDR).
3.5G Packet-
switched
HSDPA (High-Speed Downlink Packet
Access) is a mobile telephony protocol, used
for UMTS-based 3G networks and allows for
higher data transfer speeds.
A. The International Telecommunication Union (ITU) is an international organization within which governments and the private sector
coordinate global telecom networks and services.