User guide

Developers guidelines | AT commands
339 June 2010
Card
A single WML unit of navigation and user interface. May contain information to present
to the user, instructions for gathering user input, and so on.
Carrier
The frequency used by two connecting modems to transmit and receive data.
CCITT
Consultative Committee for International Telephony and Telegraphy. A European-
based advisory committee established by the United Nations to recommend
international communication protocol standards.
CD
Carrier Detect. An EIA232 signal sent from the phone modem to your computer,
usually indicating that the modem has detected a carrier signal over the
communications line.
Command line
A line of alphanumeric characters sent to the modem to instruct the modem to perform
the commands specified in the line of characters.
COM (communications) port
The name allocated to the serial port through which digital signals are exchanged
between the computer and a serial peripheral. For example COM1 and COM2.
CSD
Circuit Switched Data
CTS
Clear To Send. An EIA232 signal sent from a modem to the computer, usually
indicating that the modem is ready to receive data.
DCD
Data Carrier Connect. See AT&C.
DCE
Data Communications Equipment. This term applies to modems and to other
equipment that provide communication between data terminal equipment and the
telephone line.
Deck
A collection of WML cards.
Default value
A setting that the modem will use unless specified otherwise.
Digital transmission
A digital signal can have only two values. These can, for example, be ON and OFF,
HIGH and LOW or 0 and 1. A digital signal is usually transferred by means of a voltage
which is either HIGH or LOW. Conventional modems communicate by means of audio
tones which can use the analog telephone network. The modem links through your
mobile telephone to a digital network and therefore has no need to use audio
encoding. However, when you use your mobile telephone for a voice call, the analog
signal from the microphone must be converted into a digital signal.