Fonality - Change my DTMFmode settings in VoIP - How do I?

Click on Options --> VoIP

Click the VoIP account from the lower list that you would like to edit

Click the + symbol next to the word Advanced

Locate the DTMF options (in the right-hand column) - choose a new DTMF type from the drop-down (contact your carrier for the proper value; oftentimes RFC2833 is used, but not always)

Click Update VoIP Account