The DTMF mode is a setting that governs how Dual Tone Multi Frequency signalling is to be performed.
| Mode | Description |
| Compatibility | Use RFC2833 by default but switch to inband when reciever does not support RFC2833. |
| RFC2833 | Send DTMF information as RTP messages. |
| SIP INFO | Send DTMF information as SIP messages. |
| Inband | DTMF tones are generated by the calling device. |