How to send DTMF signals of different duration with different interval in Asterisk?

Question

Asterisk

Good afternoon. I can not understand how to adjust the period and duty cycle of DTMF signals. The essence of the task: an outgoing call, Asterisk waits until the other side is answered and then generates a pause, DTMF, pause, DTMF, pause, DTMF ...... pause, disconnection. The problem is that the duration of all pauses and DTMF is completely different.
The most working (far from final) was the option below. Although the duration between DTMFs is adjustable, although the DTMFs themselves are exactly the same length.

exten => _.,1,Dial(SIP/trunk/${EXTEN},,M(send_dtmf))
exten => _.,n,Hangup

[macro-send_dtmf]
exten => s,1,Wait(1.5)
exten => s,n,SendDTMF(1,0,200)
exten => s,n,Wait(1.5)
exten => s,n,SendDTMF(2,0,400)
exten => s,n,Wait(0)
exten => s,n,SendDTMF(3,0,600)
exten => s,n,Wait(4)
exten => s,n,SendDTMF(4,0,800)
exten => s,n,Wait(2)
exten => s,n,Hangup

What am I doing wrong, in which direction to dig? I have not worked with Asterisk before, it is needed for a one-time solution to an existing problem. Asterisk 13.14.1, SIP, GSM-VOIP gateways, mobile phones are used. Thanks in advance.

Answer 1

And in what mode does DTMF go from Asterisk towards the GSM gateway?
Maybe Asterisk generates DTMF in accordance with rfc2833, and the sound tones are reproduced by the GSM gateway itself (as it wants / can)?