DTMF for telephony integrations

You can enable and configure DTMF (Dual-tone multi-frequency signaling) for telephony integrations. When enabled, end-user telephone key-presses are converted to normal text and processed as end-user input by the agent. This conversion can be as simple as the characters associated with telephone keypresses (12*34#), or you can use regular expressions (Regex) for more complicated sequences.

Matching rules

DTMF settings have three different matching rules:

You can associate DTMF patterns with individual intents and entities to trigger a match to end-user input sequences. When you enable DTMF globally, system entities are enabled by default.

System entity rule

System entity rules are enabled by default when you enable DTMF.

Type name DTMF pattern Example
sys.percentage any integer number 29 -> 29%
sys.temperature any integer number 30 -> 30C or 30F
sys.phone-number any digit sequence 4081111111
sys.date (depending on locale) YYYYMMDD (en-us) or MMDDYYY 20231001 -> 2023-10-01, 10-01-2023 -> 10-01-2023
sys.zip-code any digit sequence 94043
sys.number digit sequence with period represented by '*' key 123 -> 123, 123*45 -> 123.45
sys.cardinal any digit sequence 12345
sys.number-integer any digit sequence 12345
sys.number-sequence any digit sequence 12345
sys.ordinal any digit sequence 12345


This section outlines the additional settings that you can configure when you enable DTMF.

Finish digit

This setting controls the keypress that will immediately terminate DTMF input, without waiting for any more input. It is common to use # for this setting. The finish digit is not included in the converted end-user input. For example, if the finish digit is #, and the input is 123#, then the converted end-user input provided to agent processing is 123.

Interdigit timeout duration

An end-user might pause while entering a sequence of keypresses. If this pause duration is greater than the interdigit timeout duration, Dialogflow aborts DTMF processing for the sequence.

If Dialogflow aborts DTMF processing, it provides the unconverted sequence captured up to that point to the agent as end-user input. This input is unlikely to match any intent or form parameters, so Dialogflow will likely invoke a no-match event.

When using the console, this field is in seconds.

Endpointing timeout duration

After a match for a keypress sequence is made, Dialogflow continues to process keypresses. Endpointing timeout duration is the duration that Dialogflow will wait for more input after a match is made before ending detection. This behavior handles scenarios where the sequence is a variable length, like unbounded numbers.

If the end-user pauses entry for than the time set in endpointing timeout duration, Dialogflow aborts DTMF processing and converts the currently-matched sequence as it normally would.

Enable DTMF

You can enable DTMF for at the agent, page, or parameter level. DTMF will be applied to everything within that scope. This section describes enabling DTMF for an agent as an example. You can also enable DTMF using Page settings (pages), Flow settings (flows), or by selecting a parameter and viewing the settings menu. In all cases, DTMF settings are found at the bottom of the page.

  1. Go to Agent settings and select the Speech and IVR tab.

  2. Go to the bottom of the page and click the Enable DTMF checkbox.

  3. Set the values for Finish digit, Interdigit timeout duration, and Enpointing timeout duration. DTMF is now enabled for everything within the scope of that agent. If set at a lower level, these settings now override any upper-level settings. Any active intents or entity types of the active slots within that scope might be triggered if they have DTMF patterns defined.

Add a DTMF pattern to an intent

  1. In the left-hand navigation menu, select the Manage tab and click Intents.

  2. Select an intent from the list that appears and go to the DTMF pattern box.

  3. Enter a DTMF sequence. You can use regex patterns in cases of more complex DTMF patterns.

  4. Click Save to save your changes.

Add a DTMF pattern to an entity

  1. In the left-hand navigation menu, select the Manage tab and click Entity types.

  2. Select an entity type from the list that appears. Go to the DTMF Pattern column in the Entities table.

  3. Set a DTMF pattern for each entity in the table. You can use regex patterns in cases of more complex DTMF patterns.

  4. Click Save to save your changes.

Use DTMF in the simulator

You can test your DTMF configuration in the Console simulator.

  1. In the Dialogflow Console, click Test Agent in the upper right hand corner of the screen.

  2. In the panel that pops up, click the + symbol next to the Talk to agent text input box. Select DTMF.

  3. Enter the DTMF pattern you want to test and the DTMF finish digit. Make sure that the Send new DTMF input box is checked, then click Send. The response to the DTMF input will appear in the simulator.