T68i
White Paper, April 2002
28
Modem and ATcommands
TheT68icontainsacompleteGSM/GPRS
modem. This providesdata and e-mail
communication,as well as Internet/intranet
access,for a connected PC, PDA or handheld
device. Oncethe PC/PDA is connected to the
phone using a cable, Bluetooth wireless
technology or infrared, and the appropriate
softwareis installed, the modem in the phone
works in a similar way to a PC Card modem, or an
external modem.
In the T68i, AT commands are used for:
• controlling the data communication
between the PCand the remote service
• configuringand requesting settings and
behaviours in the phone, from a connected
PC or PDA

GSM data communication

The built-in data capability turns the phone i nto a
modem when connected to a PC/PDA. The T68i
offers the userdata connection anytime,
anywhere,unmatched by fixed telephone
networks. Each GSM channel is divided into eight
repeatingtime slots. A normal GSM voice or data
callis circuitswitched, and only one time slot is
used foreach call. The data speed is therefore
limited to 9,600 bps. For moreinformation, see
“Built-in GSM data modem technical data” on
page 65.

High Speed Data gives a faster speed

High Speed Data(HSCSD) increases speeds for
circuitswitched data by allowing the phone to
usea coding scheme with a high capacity, and to
use two time slotsfor receiving data. The
download speed is increased to up to 28,800
bps. The speedfor sending datais limited to
14,400 bps.The data rate can be increased
several timesby the use of rate adaption,
interworkingwith ISDN. This also provides
additionalfeatures, such as quick call set-up
capability.

GPRS enables constant connection

and high speed

With GPRS, the connection is maintained
“constantly”, and data is transmitted in packets.
Pricingof GPRS can be dependenton the actual
use of bandwidth, whichmeans very low cost
when no data is sent or received, while the phone
remains connected. When transmitting large
amounts ofdata, bandwidth can be increased
automaticallyto allow faster transmission speed,
up to 64,200 bps download speed.

AT commands support

This sectionoutlines the AT commands
supportedby the T68i. The information here can
be of use for advanced users, to indicate the
possibilities they have to:
• develop new communicationssoftware
• addthe T68i to an application’s list of com-
patible modems
• adjustthe settings of their mobile tele-
phone and modem
The modem in the T68i supports the V.25ter
command set, which is the standard
communicationset used by modems.
TheT68iiscompatiblewithindustrydefacto
extensions, ETSI 07.05, 07.07 and 07.10.

Overview of ATcommand functions

AT commands are used to configure the mobile
telephone, to request information about the
currentconfiguration or operational status of the
mobilephone, and to test availability and request
the rangeof valid parameters, when applicable,
for an AT command.
Thebuilt-in modem can be set to any one of three
modes of operation.These are:
Off-line command mode
The command mode for entry of AT commands,
when the device is first turned on.
On-linedatamode
Allows “normal”operation of the built-in modem,
for exchangingdata or facsimiles with a remote
modem.
On-line commandmode
Forsending AT commands to the built-in modem
while remainingconnected to a remote modem.