US Robotics 56K USB Modem User Manual page 19

C<value>—Carrier Control
Controller-based modems support this command to ensure backwards compatibility with communication
software that issues the C1 command. However controller-based modems do not support the C0
command. The C0 command may instruct some other modems not to send carrier (i.e., it puts them in
receive-only mode).
Result codes:
• OK if <value> = 1.
ERROR if <value> ≠ 1.
•
Table 4. C<value> Commands
Command
C1 Normal transmit carrier switching (default).
D<dial_string>—Dial
Use this command to instruct the modem to begin the dialing sequence. The dial string, which is made up
of the telephone number and dial modifiers, is entered after the D command.
A dial string can be up to 60 characters long. Any digit or symbol may be dialed as touch-tone digits.
Characters such as spaces, hyphens, and parentheses are ignored by the modem and may be included in
the dial string to enhance readability.
Result codes:
• CONNECT if a connection is established and the extended result code parameter (X<value>—Select
Result Code and Monitor Call Progress on page 21) is equal to 0.
• CONNECT <rate> if a connection is established and the extended result code parameter is not equal
to 0.
• NO CARRIER if a connection cannot be established or the modem aborts the connection on request of
the host system.
• BUSY if the W or @ modifiers are used and a busy signal is detected.
• NO ANSWER if the @ modifier is used and the remote ring followed by 5 seconds of silence is not
detected before expiration of the connection timer (S10—Automatic Disconnect Delay on page 99).
• NO DIALTONE if tone detection is enabled or the W modifier is used and no dial tone is detected.
• OK if the command is aborted or DTR is turned off by the host system when the data terminal ready
control (&D<value>—Data Terminal Ready (DTR) Control on page 24) is not set to 0.
• ERROR if the modem is in online command mode when receiving the dial command. )
Table 5. Dial Modifiers
Modifier Function Name
L Dial the last number
P Select pulse dialing
T Select tone dialing (default)
W Wait for dial tone
Function
Instructs the modem to dial the last number dialed. This
modifier is valid only if it is the first symbol of the dial string. All
consecutive characters are discarded.
Instructs the modem to wait for a second dial tone before
processing the dial string.
56K USB Modem
Description
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Command Reference - 13
User Guide