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This guide connects Retell AI to Slack so team members can start outbound calls with a slash command. After each analyzed call, Retell posts the result to the originating channel.

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Before you start

  • Permission to install apps in the target Slack workspace
  • A Retell account with an API key, configured voice agent, and outbound phone number
  • A Slack channel where Retell can post call results; invite Retell AI before using a private channel
  • A valid destination number in E.164 format, such as +15551234567
Use your own API key, webhook URL, agent, caller ID, channels, and test numbers. The screenshots use sample or masked values.

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Install Retell AI in Slack

1

Add Retell AI to the workspace

Open the Slack App Directory, search for Retell AI, select Add to Slack, and choose the workspace you want to connect.
Slack App Directory listing for Retell AI with the Add to Slack button
2

Approve the requested permissions

Review the Slack permissions, then select Allow to finish installing the app.
Slack OAuth permission screen for Retell AI with the Allow button

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Connect Slack and configure Retell

1

Open the Retell AI App Home

In Slack, open Apps → Retell AI → Home. If the workspace is not connected, select Connect Slack and approve access.
Retell AI App Home showing the Connect Slack option
2

Launch the configuration wizard

From App Home, select Launch configuration wizard. Sign in to Retell if required, or continue without signing in when your Retell account is already configured.
Retell AI App Home showing the Launch configuration wizard button
3

Set the webhook key

In the Retell dashboard, go to Settings → API Keys. Copy an existing key or select Add Key to create one. Open the key’s ⋮ options menu and select Set as webhook key, then copy the key value.
Retell API Keys page with the key options menu open and Set as webhook key highlighted
The API key must have the webhook option enabled. Post-call analysis data is only posted back to Slack when the key is designated as a webhook key.
4

Save the API key

Paste the webhook key into Retell API Key and select Save API key. Confirm that the status shows Saved before continuing.Retell AI supports only one active webhook integration at a time. If you are also using Notion or Zoho, choose which integration receives webhook events.
Retell setup wizard showing the Retell API Key field and Save API key button
5

Choose the outbound caller ID

Select the Retell phone number used for outbound calls. If an agent option appears, choose the default agent or keep the Retell account default.
Retell setup wizard showing the outbound caller ID and agent options
6

Set the default notification channel

Choose the Slack channel that receives results when a call does not specify one. For a private channel, first run /invite @Retell AI in that channel.
Retell setup wizard showing the default Slack notification channel selector

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Register the Retell webhook

1

Copy the generated webhook URL

In the setup wizard, find Register the Webhook URL in Retell and select Copy webhook URL.
Retell setup wizard showing the generated webhook URL and Copy webhook URL button
2

Add the webhook URL to the Retell agent

Open the Retell dashboard, select Agents, and open the agent used for Slack. Expand Webhook settings, paste the URL into Agent Level Webhook URL, and select Test. Under Webhook Events, make sure call_analyzed is enabled so Retell can send the post-call result. Save or publish the changes.
Webhook settings with the agent URL field, Test button, timeout, and event selection. The URL is not yet configured.

Paste the integration URL into Agent Level Webhook URL.

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Place an outbound call from Slack

Use the slash command for the fastest end-to-end test.
1

Run the slash command

In a channel where Retell AI can post, enter the command below with a valid E.164 destination number. Slack displays a private confirmation when the call starts.
Slack channel showing the retell-call slash command with an E.164 destination number
2

Review the post-call message

After Retell analyzes the call, review the Slack message for the summary, duration, direction, sentiment, transcript details, and recording link.
Slack message containing the Retell AI post-call summary, call details, and recording link

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Troubleshooting