November 10, 2014 - 11:58am, 5267 views
Hello, Good morning,
i have a question over sending in-band / out-band DTMF tones.
Does anybody know how to configure BGS2-E for sending DTMF out-band ?
To send DTMF during active voice call or in alert state you can use AT+VTS command.
Available values: 0-9,#,*,A, B, C, D
You can send up to 29 tones in one command.
You should also configure AT^SM20=0 for sending tones during the active voice call.
It is also possible to send the tones with the dial string (ATD command). If the dial string contains the call modifier "p" the digits after this call modifier till the end are handled as DTMF tones, which are transmitted at connect state for voice calls.
Please check the AT Commands Specification document for more details.
DTMF is sent, but the problem is that it's sent in-band, which is against 3GPP TS23.014. So the question is whether it's possible to change this behavior, to use out-of-band signaling. In the AT Command Specification I could find that audio mode 6 is specific for DTMF:Audio mode 6: Tip and Ring interface for end-to-end DTMF transmission.Can someone confirm that with changing the audiomode with AT^SNFS to a different value, the device will use out-of-band DTMF or it doesn't support out-of-band DTMF at all?Best Regards:Peter
Each audio mode has different predefined audio parameters for input and output. These parameters can be changed by other audio commands. So mode 6 could be best choice for receiving DTMF's which come to the module as analog tones.
DTMF's are always transmitted to MSC as out of band signalling. Module does not generate the tones. They are generated by MSC.
Hope that helps,
Hi Bartłomiej! Thanks for the answer, the issue is that from MSC side we don't see that the device would be sending out-of-band signalling(Start/Stop DTMF), although we know the it's sending DTMF.I guess there is still the possibity that the application is somehow using a tone generator coupled to the microphone instead of using the AT+VTS command.Best Regards:Peter
This is always possible.
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