# Alerts

Alert channels, phone and SMS alerts, email recipients, and verifying webhook signatures.


Each monitor alerts the channels you pick on its form. New monitors alert every channel by default.

## Channels

| Channel | What you need |
|---|---|
| Slack, Discord, Microsoft Teams | An incoming webhook URL from the app. |
| Telegram | A bot token from @BotFather and your chat ID. |
| PagerDuty | An Events API v2 routing key. Incidents open and resolve automatically. |
| incident.io | An HTTP alert source ID and token. Alerts resolve automatically. |
| ntfy | A topic name (pick one that's hard to guess) and the free ntfy app. |
| Pushover | Your user key and an application token. |
| Email | Up to 10 addresses. Addresses outside your team get a confirmation link first. |
| SMS and phone call | Team and Business plans (3 during the free trial, to try it). Verify the number under *Phone numbers* first. |
| Webhook | Any URL that accepts a POST. |

Use **Send test** on a channel to check it works.

## Phone calls and SMS

Team includes 100 calls and texts a month, Business 500. Numbers must be verified with a code before they can receive alerts. Calls are only made for outages, not recoveries, and read the alert twice.

## Webhooks

A webhook channel POSTs every alert as JSON to your URL, optionally signed. The payload, delivery
rules, custom body templates and signature checks in Python, Node and Go are in [Webhooks](/docs/webhooks).