Specifications

AN93
28 Rev. 0.8
This restriction also applies to all commands beginning
with the “+” character (eg. +VCID).
For example, AT:U42,0022:U43,0010<CR> is an illegal
command and causes unpredictable behavior. Also, \Tn
commands may not be used on the same command line
as an :U or :R command.
The AT command execution time is less than 200 ms.
The host must wait for a response after each command
(e.g., “OK”) before issuing additional commands. The
reset recovery time (the time between a hardware reset
or the carriage return of an ATZ command and the time
the next AT command can be executed) is less than
300 ms.
Characters must not be sent between the ATDT
command and the protocol message. During this time,
the modem is in a transition between command and
data modes. Any characters sent during this time will
cause the connection attempt to fail.
Blind dialing (dialing without waiting for dial tone) is
enabled by ATX0, ATX1, and ATX3. Whether or not
blind dialing is enabled, use of the W dial modifier
causes the modem to look for a dial tone before dialing
the number string after the W. For example, an AT
command string, “ATX1 DT 9, W123456<CR>”, causes
the modem to dial 9 immediately without detecting a dial
tone but does not dial 123456 until a dial tone is
detected.
AT commands and result codes are listed in Tables 20–
24. The default settings are shown in bold type.