Integrations / Slack
Slack AI voice agents that tell your team what just happened
The agent answers the phone, and when a call needs a person it posts the caller, reason and urgency to a Slack channel with chat.postMessage.
Front desk agent
Answers calls and alerts the team in Slack.
Instructions
Answer hours, location and refund policy questions from your knowledge. If the caller reports something urgent or asks for a callback, post a short message to Slack with their name, the reason and how urgent it is. If it is an emergency, post first, then transfer to the on-call line.
- Handoff
- On-call line
Connected tools
- Post to SlackWebhook
- Transfer to on-callTransfer
What a Slack AI voice agent can do
Open one to watch a call. The grey lines are the tools the agent calls mid-sentence.
An urgent call posts to the channel your team watches, with the caller's number and what they need from you.
Before it ends a call your instructions flag, the agent posts two or three sentences on what was asked and promised.
For an emergency the agent posts first, then transfers. Transfers are cold, so whoever answers can read the post first.
Tool definitions
Webhook tools go to POST /v1/agents/tools. Transfers are a system tool on the agent. Replace the placeholder values in capitals with your own.
Post to Slack
Posts a message to one Slack channel.
Show the JSON definition
Transfer to on-call
Cold transfer to the on-call number.
Show the JSON definition
Set it up
No native connector. The tool calls Slack's Web API with a bot token from a Slack app you create, stored as a secret. Vendor details read in November 2026.
Create a Slack app
Create an app for your workspace, add the
chat:writebot scope, install it, and copy the bot token. It starts withxoxb-.Invite the app to the channel
Add the app to the channel it posts in, and copy the channel ID from the channel details.
Add the tool
Store the bot token as a bearer secret and set the channel ID as a constant, so the agent can only post to that channel.
Test an escalation
Call the agent, report something urgent, and check the message in Slack.
Before you build
Slack reports errors in the body
A failed post comes back with ok set to false and an error code such as not_in_channel or channel_not_found. If nothing shows up in Slack, look for that code in the tool's response.
Why not an incoming webhook
Slack's incoming webhooks also post to a channel, but their URL is the credential. A webhook tool stores its URL as plain configuration and hides only secrets, so this page uses a bot token.
One message per second
Slack allows about one message per second to a channel, with short bursts. One post per call stays well inside that, but don't have the agent post on every turn.
Post-call summaries
To post a summary after each call, including calls where the agent never used the tool, send Cartesia's post-call webhook to a service of yours that calls chat.postMessage.
Use cases for teams on Slack
More integrations
Enterprise-grade security
HIPAA compliant

SOC 2 Type 2

GDPR
Slack AI voice agent FAQs
Can an AI voice agent send a Slack message?
Yes. The agent on this page answers the phone, and when a call needs a person it posts the caller, the reason and the urgency to a Slack channel with chat.postMessage, using a bot token from a Slack app you create. It doesn't read or answer Slack messages.
How do I connect Slack to an AI voice agent?
Create a Slack app with the chat:write bot scope, install it, and copy the xoxb- bot token. Invite the app to the channel, copy the channel ID, and add the webhook tool with the token as a bearer secret and the channel ID as a constant.
Can the agent post a summary of each call to Slack?
Yes, through Cartesia's post-call webhook rather than a tool. The webhook payload includes a summary, so a service of yours can post it with chat.postMessage, including for calls where the agent never used the tool.
Can it post to more than one Slack channel?
Yes, with one tool per channel, each with its own channel ID as a constant. Keeping the channel fixed stops the agent from posting somewhere you did not choose.
Why doesn't the agent use a Slack incoming webhook?
An incoming webhook's URL is the credential, and a webhook tool stores its URL as plain configuration and hides only secrets. A bot token stored as a secret keeps the credential hidden.
What does a phone agent that alerts Slack cost?
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