User's Manual

A - Answer Mode
When the A command is entered, the modem switches to the “Off-Hook”
condition when ringing appears in the answer mode and takes over control of
the telephone line connected. In this way, the modem transmits in the upper
frequency band (upper channel).
If further commands are entered after the A command before a connection has
been made, the modem interrupts the establishment of a connection, switches
to command mode and issues a NO CARRIER message.
If no carrier is received from the remote station after the waiting time which is
set in the S7 Register, the modem responds with a NO CARRIER message
and returns to command mode. If the modem does receive the carrier signal, it
issues a CONNECT message and switches to Data mode.
=> If the handset is not replaced after the data transmission has been
completed, the connection remains online and you will continue to pay for this !
A/ - Repeat Last Command Line
The A/ command causes the modem to repeat the command line which is
stored in the command buffer, e.g. it will dial again, if the line is busy. This
command is entered without AT and no reply is issued.
=> A command line remains in the repetition buffer until the modem
receives a new command. The data format should not be modified in the
meantime.
B - BELL/CCITT Standard
The B command permits change-over between CCITT and Bell standards at
300 or 1200 bps. At 300 bps, this command will select between Bell 103 and
CCITT V.21, while at 1200 bps it will select between Bell 212A and CCITT
V.22.
ATB0 CCITT V.22, V.21
ATB1 Bell 212A, Bell 103 (factory setting)
=> The B command refers only to connections at 300 or 1200 bps. All other
speeds use the CCITT standard.
2-4 AT COMMANDS: DATA MODEM