2G - 2nd generation
Commonly used term to describe 2nd generation mobile cellular systems such
as GSM and DCS1800.
2.5G - 2 and one half generation
Commonly used term to describe the interim generation (between 2nd generation
and 3rd generation) cellular mobile systems such as GPRS.
3G - 3rd generation
Commonly used term to describe 3rd generation mobile cellular systems such
as UMTS.
'500' Telephone Service
US: A service providing
the ability to take a telephone number to different locations. A consumer
subscribing to 500 service receives a 500 "area
code" number that can be programmed to deliver calls wherever the consumer
travels in the United States and in many locations around the world. Individuals
calling 500 subscribers dial 500 plus a 7-digit number (NXX-XXXX). When a
call is placed to a 500 service telephone number, the originating local
exchange carrier (LEC) uses the NXX of
the dialed number to identify the carrier serving the owner of the 500 number.
The LEC then routes the call over the appropriate carrier's network.
'711' Telephone Service
US: An telephone
number used nationwide to facilitate access for individuals with hearing or
speech disabilities to Telecommunications Relay Services (TRS), a telephone
transmission service designed to give persons with hearing or speech disabilities
'functionally equivalent' access to the telephone network. In 1997 the FCC
mandated the assignment of 711, an abbreviated dialing arrangement of
less than the standard 7 or 10 digits, on a nationwide basis. (See also Telecommunications
Relay Services)
'900' Telephone Service
US: A calling service
to which businesses subscribe providing a method for them to deliver information,
advice, or consultations by telephone. Individuals calling a 900 number to
reach a business subscribing to this service dial 900 plus a 7-digit number
(NXX-XXXX). When a call is placed to a 900 service telephone number, the originating
local exchange carrier (LEC)
uses the NXX of the dialed number to identify the carrier
serving the business operating the 900 number service. The LEC then routes
the call over the appropriate carrier's network.
911
US: A telephone number
for notifying police, fire, or medical authorities of an emergency situation.
Telephone companies rely on data bases to route emergency calls. The 911 database
actually consists of two separate databases, the Management System, which
contains the Master Street Address Guide, and the Selective Routing/Automatic
Location Identification (SR/ALI) database, which forwards the 911 call to
the appropriate public safety answering point (PSAP).
A PSAPis a centralized agency or facility operated by the local government
that receives and responds to emergency calls. (see also enhanced
911)