In the Azure Portal, search "monitor" and click on the Monitor icon.

On the Monitor page, click on Alerts in the left column and then Action Groups.

On the Action groups page, click on Create to create a new action group.

On the basics page, you'll link your subscription and resource group. Then, you'll name the action.

Under Notifications, you'll choose the notification type and name the notification. Choose Email/SMS message/Push/Voice for text message.

A menu for directing the notification will pop-up on the right of the screen. Check off SMS for a text message and enter the phone number that you want to receive the text messages.

Afterwards, you can click "Review and create" to complete the setup.

Navigate to the Rules page on the side menu bar.

Click on New to create a new rule.

First, you'll need to name the alert and toggle the Enable option to turn it on. Then you can select the device to receive alerts for.

You'll setup conditions for the rule. You can have the rule be triggered if all or some of the conditions are true. The Time aggregation option can limit the number of alerts you receive. For example, if you select 60 minutes then you will only be alerted once per hour if a condition is true.

Under Telemetry, you'll select the data feed to monitor, as well as an operator; such as less than, equal to, etc. Under Value, you'll enter the value to watch for.

Under Actions, you'll select Azure Monitor Action Groups.

Select the Action Group that you setup earlier from the dropdown menu. When you're finished, save your Rule and you're ready to receive text alerts.