# What does DTMF mean?

DTMF means **Dual-Tone Multi-Frequency** (dual-tone multi-frequency). Put more simply, these are key tones.

**When do I need DTMF?**

For calls to a **voice computer**, which requires input via key tone, this is done via DTMF. DTMF is also used for a call to the **sipgate voicemail** , since it asks for a PIN via key tone. But DTMF is also needed for various telephony features such as **call swapping and transferring** .


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