VoIP - DTMF
A niche feature, but with call recording enabled when the audio file is emailed to you any DTMF presses that the user presses is also included in the email as an XML file. The body of the email also includes the DTMF presses but the XML file includes timestamp details.
eg here is an XML file for a DTMF of '5' presses 6 seconds in to the call and it was pressed for 250ms:
<?xml version="1.0" encoding="UTF-8"?> <dtmf channels="2"> <dtmf channel="1" key="5" time="6000" length="240"/> </dtmf>