asterisk users - Dec 2019 - How to: send dtmf back to the calling channel from post-answer subroutine executed on outbound channel

I have a customer who wants me to send a DTMF on the calling channel if the
called channel says any word. So I am using
[my_gosub_routine]

exten => s,1,NoOp(ARG1=${ARG1} ARG2=${ARG2})
 same => n,Playback(hello)
 same => n,Return()

[default]

exten => _X.,1,NoOp()
 same =>
n,Dial(PJSIP/alice,,U(my_gosub_routine^my_gosub_arg1^my_gosub_arg2))
 same => n,Hangup()

Is there a way to send DTMF back to the caller from [my_gosub_routine]?
If I use sendDTMF at the moment, it will be heard only by the callee, and
only the caller must hear it.
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