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How DTMF Works

DTMF (Dual-Tone Multi-Frequency) is the signal produced when someone presses keys on a phone keypad. Enable DTMF when a phone-call agent needs to:
  • send keypad tones to external IVR systems
  • collect caller keypad input, such as menu choices or short account identifiers
DTMF is for phone calls only. Web calls and chat sessions do not have a phone keypad, so DTMF does not apply there.

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Where To Enable It

Access: Open an agent, go to Call Flow, and scroll to Keypad Input. Turn on Enable DTMF during calls.
DTMF is currently an Alpha setting. The dashboard exposes one toggle; keypad timing, capture mode, clear digit, termination key, and buffering behavior use platform defaults.

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What Is Supported

When DTMF is enabled, the platform registers keypad tools for the call session. It can send tones to the phone leg and receive caller keypad presses from SIP DTMF events. For exact-length input, such as “collect 4 digits”, the platform uses native fixed-length keypad collection when available. For variable-length or menu-style input, it falls back to the platform’s internal collector.

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Prompt Examples

Use short, explicit phrasing: 
"Press 1 for billing, 2 for support, or 3 for sales."
After the digit arrives, confirm the meaning, not the mechanism: 
"Got it — I'll help with support."
Use DTMF for short numeric input that is easier to enter than to say: 
"Please enter the last 4 digits of your account number using your keypad."
Confirm safely: 
"Thanks. I found the account ending in 2457."
Do not repeat full sensitive values back to the caller unless your workflow truly requires it.

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Always offer a voice fallback

Not every caller will want to use a keypad. 
"If you prefer, you can also say the number out loud."
That keeps the flow accessible for callers on speakerphone, softphones, or devices with awkward keypad access.

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Testing DTMF

1

Use a phone test

Open Test on the agent and choose Phone so you are testing a real phone leg.
2

Test caller keypad input

Ask the agent for a simple keypad response such as 1 or a short numeric identifier.Confirm the agent reacts correctly and the call does not stall if no key is pressed immediately.
3

Test external IVR navigation

If your agent must navigate another phone tree, run a live test against that real number or SIP destination and verify the downstream IVR accepts the tones reliably.
4

Test the fallback path

Intentionally avoid pressing keys once so you can confirm the agent retries cleanly or offers a voice alternative.

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Best Practices

  • Ask for one keypad action at a time.
  • Offer a voice fallback, such as “You can also say the number out loud.”
  • Confirm only the safe part of sensitive values, such as the last 4 digits.
  • Test the exact carrier, phone number, or SIP route you will use in production.

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Next Steps

Transfer Tools

Configure live transfer destinations and downstream call handling

Voicemail Handling

Test phone outcomes such as human answer vs voicemail

Phone Numbers

Set up the phone infrastructure required for live keypad interactions

VAD & Turn Detection

Tune interruption and pause behavior around keypad-driven flows