DTMF double tones

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dcitelecom

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Oct 20, 2021
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A DID on our fusionpbx system is forwarded to an external voicemail system. When we enter digits they are malformed at the endpoint and the caller cannot navigate the IVR.

It seems the carrier is sending a mix of rfc2833 info and/or inband and the voicemail IVR system appears to be listening to both inband and RFC2833 tones which is causing the issue. I currently use "action block_dtmf peer" in the dialplan to make it work but I am wondering if there is a better way to ignore the double tones or filter out the second signal in the outbound dialplan? Liberal_DTMF is already off in internal sip settings and deduplicate_dtmf did not work.
 

hfoster

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Jan 28, 2019
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Think you'll want this on your outbound route:


Code:
<action application="set" data="dtmf_type=rfc2833"/>

The FreeSwitch documentation is a bit shitty for DTMF, so I'm not sure if you need to enable anything inbound to intercept it like 'start_dtmf'

I found this also, but it doesn't seem much use:

 
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