Answer a call a, Remote disconnection, Extended error report +ceer – Multi-Tech Systems MMCModem GPRS (MTMMC-G) User Manual
Page 21: Dtmf signals +vtd, +vts
Chapter 5 – Call Control Commands
Multi-Tech Systems, Inc. Wireless GSM/GPRS AT Commands (Document Number S000293I)
21
Answer a Call A
Description:
When the product receives a call, it sets the
RingInd signal and sends the ASCII “RING” or “+CRING:
the application to accept the call with the ATA command.
Values:
No parameters.
Syntax: ATA
Command
Possible responses
RING
Note: Incoming call
ATA
Note: Answer to this incoming call
OK
Note: Call accepted
ATH
Note: Disconnect call
OK
Note: Call disconnected
Remote Disconnection
This message is used by the product to inform the application that an active call has been released by the remote user.
The product sends “
NO CARRIER” to the application and sets the DCD signal.
In addition, for AOC, the product can release the call if credit has expired (release cause 68 with +CEER command).
Extended Error Report +CEER
Description:
This command gives the cause of call release when the last call set up (originating or answering) failed.
Values:
No parameters
Syntax:
AT+CEER
Command
Possible responses
ATD123456789;
Note: Outgoing voice call
NO CARRIER
Note: Call setup failure
AT+CEER
Note: Ask for reason of release
+CEER: Error
OK
Note:
from GSM recommendation 04.08 or specific Call
accepted
Note: “NO CARRIER” indicates that the AT+CEER information is available for failure diagnosis.
DTMF Signals +VTD, +VTS
+VTD
Description:
The product enables the user application to send DTMF tones over the GSM network. This command is
used to define tone duration (the default value is 70 ms
± 5 ms according to 3GPP 23.014).
Values:
This refers to an integer
command. This does not affect the D command.
A value different than zero causes a tone of duration
A value of zero (default value) causes a tone duration of 70 ms
± 5 ms.
Note: The value is used modulo 256.