Chapter 5 – Call Control Commands
Multi-Tech Systems, Inc. Wireless GSM/GPRS AT Commands (Document Number S000293I) 22
Syntax: AT+VTD=<n>
Command Possible responses
AT+VTD=6
Note: To define 600 ms tone duration OK
Note: Command valid
AT+VTD=0
Note: To set the default value (70 ms ± 5 ms) OK
AT+VTD?
Note: Query current tone duration AT+VTD: <n>
OK
AT+VTD=? AT+VTD: <0-255>
OK

+VTDS

Description: The product enables the user application to send DTMF tones over the GSM network. This command
enables tones to be transmitted only when there is an active call.
Values: <Tone> DTMF tone to transmit.
Tone is in {0-9, *, #, A, B, C, D}
Syntax: Command Syntax: AT+VTS=<Tone>
Command Possible responses
AT+VTS=A
OK
Note: Command valid
AT+VTS=11
Note: To set the default value +CME ERROR: 3
Note: If the <Tone> is wrong
AT+VTS=4
+CME ERROR: 3
Note: If there is no communication
AT+VTS=”1”;+VTS=”3”;+VTS=”#”
OK
Note: Sed tone sequence 13#
Redial Last Telephone Number DL
Description: This command redials the last number used in the ATD command. The last number dialed is displayed
followed by “;” for voice calls only.
Values: No parameters
Syntax: ATDL
Command Possible responses
ATDL
Note: Redial last number 0146290800;
OK
Note: Last call was a voice call. Command valid