Ask the Expert

How do you divide DTMF transmissions?

How do you divide DTMF transmissions, such as in-band or out-of-band? Can RFC2833 be considered in-band?

    Requires Free Membership to View

In-band DTMF specifically refers to sending the DTMF digit frequencies along the same voice path as the actual speech in a conversation. This works well for an uncompressed channel using G.711, but does not work reliably when using a compressed channel such as G.729.

RFC2833 DTMF uses an out-of-band approach. The idea here is that special Real-Time Transport Protocol (RTP) even messages are sent instead of the raw tones. For example, a message is sent indicating a "DTMF digit 7" versus sending the two frequencies that make up a DTMF 7. This approach is more reliable.

This was first published in March 2006

There are Comments. Add yours.

TIP: Want to include a code block in your comment? Use <pre> or <code> tags around the desired text. Ex: <code>insert code</code>

REGISTER or login:

Forgot Password?
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy
Sort by: OldestNewest

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to: