To receive an SMS message Action alert, you'll need to add your phone number to your Adafruit account. Note that SMS message alerts are only available for IO+ accounts. Other alert types are available for free tier accounts, such as email and web hooks.

In Adafruit IO, go to the Actions tab and click on + New Action.

Then, you'll choose an Action type. Click on Reactive.

This lets you set up the Action, which is done through a logic tree with dropdown menus:

1. Select the feed that you're monitoring
2. Select the greater than or equal dropdown and enter the value that you want to monitor for the threshold
3. Select the action notification type (SMS message, email, etc)
4. Select the feed again and customize the message that you'll receive when the action is triggered

Further down the page, you can select the frequency for notifications and if you'd like to be notified when the value returns below the threshold that you're monitoring. Then you'll click Submit to save the Action.

This returns you to the Action page, where you can see the Action you just set up.

When the Action is triggered, you'll receive the notification with the message that you entered.