How Voice AI handles DTMF: the complete guide (RFC 2833 vs SIP INFO vs in-band)

DTMF is one of the most overlooked configuration details in Voice AI deployments. It only becomes visible when a caller presses a key - to enter a PIN, navigate a menu, or confirm a choice - and nothing happens. No error. No feedback. The call continues as if the keypress never occurred. I have debugged DTMF failures on three separate enterprise deployments. In every case the root cause was the same: the SIP trunk and the Voice AI platform were configured for different DTMF transmission modes an