Outgoing DTMF on PolyCom phones



Deploying some PolyCom VVX 600’s and Asterisk to power a small office PBX I found that phone users could not use DTMF tones for IVR operations. Such as “Press 1 for sales, 2 for accounting” sort of thing. As you can imagine, this makes navigating an IVR or reaching direct extensions very difficult.

Luckily, the solution was simple. I added the following lines to the configuration file, which the phone downloads from the TFTP server on boot.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!-- Application SIP Helford3 5.9.3.2857 02-Jul-19 06:06 -->
<!-- Created 10-04-2020 13:45 -->
<!-- Base profile Generic -->
<WEB_CONFIG>
        <OVERRIDES
                (OTHER CONFIG ENTRIES HERE)
                voIpProt.SIP.dtmfViaSignaling.rfc2976="0"
                tone.dtmf.rfc2833Payload="101"
        />
</WEB_CONFIG>

This should resolve the issue, in my tests this resolved the issue and users were able to operate IVR’s and enter direct extensions.

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