---
title: SMS alerts
description: Text up to ten phone numbers when a monitor goes down.
sidebar:
  icon: smartphone
  label: SMS
---

{/* Source of truth: packages/shared/src/notifications.ts — smsChannelSchema,
    MAX_SMS_RECIPIENTS = 10, phoneNumberSchema (E.164). Plan gate:
    smsNotifications in packages/shared/src/plans.ts. */}

SMS reaches a phone when nothing else does — no app, no data connection, no
notification settings in the way.

## Configuration

| Field | Value |
| --- | --- |
| `phoneNumbers` | 1 to 10 numbers in E.164 format |

E.164 means a leading `+` and country code, no spaces or punctuation:

| Country | Example |
| --- | --- |
| France | `+33612345678` |
| United Kingdom | `+447700900123` |
| United States | `+15551234567` |

Duplicate numbers in one channel are collapsed, so the same phone is never
texted twice for one alert.

:::note
SMS is plan-gated (`smsNotifications`). See [Plans and limits](/billing/plans).
:::

## Use it sparingly

SMS is the channel most likely to be ignored if it is over-used, and the one
where that matters most. Two rules keep it useful:

1. **Subscribe to `MONITOR_DOWN` only.** Recovery notifications do not need to
   buzz a phone at 4am; put those on email and Slack.
2. **Scope it to genuinely critical monitors**, ideally by
   [project](/organization/projects) rather than by listing monitors.

A phone that goes off for a staging environment gets silenced, and then it is
not an alerting channel any more.

## Limitations

- **No acknowledge link.** SMS carries the alert text only. Acknowledge from
  the dashboard, or from the email alert for the same incident.
- **Delivery is best-effort.** Carrier delays and international routing are
  outside Glowo's control. For a real on-call rotation with escalation and
  delivery guarantees, use [PagerDuty](/alerting/pagerduty).