User`s guide

AT Commands
5-8 Modem 3600
The X3 command followed by a dial command makes the modem go off
hook, wait the amount of time set in register S6 and dial the number. If
a busy signal is detected, the modem sends a BUSY message and hangs
up. If the call is completed, the appropriate CONNECT message similar
to X1 is displayed. The modem does not detect a no dial tone situation.
The X4 command followed by a dial command makes the modem go off
hook and wait for a dial tone before dialing. If a dial tone is not detected
within 5 seconds, the modem returns a NO DIALTONE message and
hangs up. If a busy signal is detected, the modem returns a BUSY
message and hangs up. If the call is completed, the appropriate
CONNECT message similar to X1 is displayed.
The X4 command combines the features of X1, X2, and X3. The factory
setting is X4.
Note
When an X2, X3, or X4 command is in effect, an appropriate
CONNECT data rate message or code is displayed as for X1.
When a blind dial command (X, X1, X3) is in effect, the
modem waits 2 seconds or the time set in S6 and then dials.
Number Code Application *RC
Some communications software packages use different number codes to
indicate the data rate of the serial port. This option selects either of two
commonly used number code sets.
Note
Asterisks in AT commands are part of the command and do
not indicate footnotes.
Command Code Set Number Operation
*RC Standard 15
18
4800 bps
9600 bps
*RC1 Alternate 11
12
4800 b p s
9600 bps