Blog - Syllable

Josh York, Christopher Zheng, Emanuel Oliveira

Jul 31, 2025

Overview

Syllable AI Agents have always been able to process DTMF inputs, but we've released a new tool that enables your agents to send DTMF signals.

The dtmf tool gives your AI Agent the power to navigate touch-tone IVRs by letting them send RFC 4733 compliant tones over the phone. It's especially useful for outbound agents that may encounter IVRs during sales, survey and marketing calls. Since your AI Agent can already speak to voice based IVRs, this completes the toolbox for running powerful outbound AI Agents.

Step 1 – Check out the new tool

The new dtmf tool is a syllable system tool that is available to all users.

Log into the Syllable Console
Click the "Tools" tab
Search for "dtmf"
Take a look at the tool schema and notice that it's interfacing directly with the Syllable System

If you don't see the dtmf tool, you can add it by clicking "New tool" and copying the JSON tool definition from System Tools.

Step 2 – Add the tool to your Agent's Prompt

Click on "Prompts"
Select the prompt that you want to update and click on "Edit"
In the Tools section type in "dtmf" and enable it
Provide the Agent with instructions on how to use the tool inside of the prompt
Click Save

Step 3 – Test your agent

Click on "Agent", select your Agent and click on "Start Session"
Tell the Agent to enter a digit to achieve the goal in the prompt
You should see the "dtmf" tool be called in the chat window

Step 4 – Place an outbound call to test your agent

Click on "Campaigns" and then "New Campaign"
Set the name, select your Agent's outbound number and set the rate
Set the campaign hours
Select "Batches", "New Batch" and enable auto-run
Download the CSV template, add your target IVR phone number
Upload the CSV file and watch the calls light up

Go to Sessions to monitor the call and verify that the agent successfully navigated the IVR.

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