Modems guidelines and functions

AT: - Command line prefix. The ATtention command precedes all other commands listed below except for A/ and the escape code. For example, the command DT would be typed ATDT.

A/:- Repeat last command (not to be preceded by AT)

A: - The modem is set to answer mode and goes offhook immediately. Answer without waiting for ring.

Bn: - Bell mode - set 1200 bps protocol compatibility Selects V.22 or Bell 212A in the 1200bps mode. n=0, CCITT V.22 with 2100Hz Answer Back Tone. n=1, Bell 212A with 2225Hz Answer Back Tone.

Cn: - Carrier state: n=0, OFF n=1, ON Eg. C1 = carrier state on.

Dn: - Dial telephone number. Dial the number immediately following this command, where n is the number combined with other dial subcommands as shown below. Any combination of the subcommands listed below may be strung together to perform the desired dialing sequence. The number is dialed in the call progress or blind mode depending on register S11.
Dial Subcommand and Function
T: - Touch Tone Dialing
P: - Pulse dialing (some modems use by default to Pulse if T or P not used.
R: - Reverse mode. Puts modem in answer mode immediately after dialing. Use answer frequencies when originating a call.
S=n: - Dial a stored number. The numbers are stored in the registers of the microcontroller.
n=0, 1, 2, 3 - stored number that has been previously stored in non-volatile RAM, using &Zn command.

W: - Wait (for seconds dial or access tone). Wait for a continuous tone before dialing the next number. Useful for dialing MCI or Sprint. The modem waits S7 seconds (see Appendix B about registers) for the tone. If the tone is not heard, BUSY or NO DIALTONE result code is issued.

@:- Wait for a "quiet answer" - one or more rings followed by 5 seconds of silence - for the length of time defined.

, :- (comma) - Pause (a delay in dialing sequence). Pause the length of time specified by S8 (default time = 2s) each comma equals the pause length specified. You may use as many commas as you like. E.g. To disable call waiting in most areas use, *70,,312-666-9000 to connect to UIC .
! : - Flash (on-hook for 1/2 second). This character can be used to go temporarily on-hook in order to get a new dial tone.

;:- Return to command mode after dialing. This command can only be placed at the end of a dial command

0-9 # * ABCD: - Digits and characters that may be used in dialing. # * and ABCD may only be used when tone dialing.

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