Other important types of data

Dual Tone Multifrequency (DTMF) digits and telephony tones & signals

To convey signaling information in the audio channel dual tone multifrequency signaling is often used.

FAX

Another use of telephony connections is for FAX.

Why is FAX still important?

See RFC 4733, RFC 4734, and RFC 5244.

Slide Notes

[RFC 2833] H. Schulzrinne and S. Petrack, ‘RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals’, Internet Request for Comments, vol. RFC 2833 (Proposed Standard), May 2000 [Online]. Available: http://www.rfc-editor.org/rfc/rfc2833.txt Links to an external site.

[RFC 4733] H. Schulzrinne and T. Taylor, ‘RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals’, Internet Request for Comments, vol. RFC 4733 (Proposed Standard), Dec. 2006 [Online]. Available: http://www.rfc-editor.org/rfc/rfc4733.txt Links to an external site.

[RFC 4734] H. Schulzrinne and T. Taylor, ‘Definition of Events for Modem, Fax, and Text Telephony Signals’, Internet Request for Comments, vol. RFC 4734 (Proposed Standard), Dec. 2006 [Online]. Available: http://www.rfc-editor.org/rfc/rfc4734.txt Links to an external site.

[RFC 5244] H. Schulzrinne and T. Taylor, ‘Definition of Events for Channel-Oriented Telephony Signalling’, Internet Request for Comments, vol. RFC 5244 (Proposed Standard), Jun. 2008 [Online]. Available: http://www.rfc-editor.org/rfc/rfc5244.txt Links to an external site.

Transcript

[slide94] As we mentioned, other kinds of data. We talked about faxes earlier. Another one is DTMF, dual-tone multi-frequency. Right, those are the dial tones when you heard going tweet, tweet, tweet, tweet as you type the number. Well, there are lots of services that use that information. Why? Because users often have that as the only input device that they have. It's becoming less and less common, but it's still present.