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.
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.
2
Approve the requested permissions
Review the Slack permissions, then select Allow to finish installing the app.
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.
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.
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.
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.
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.
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.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.
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.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.
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.