As part of any paid plan in Expiration Reminder, you can SMS or mobile notifications to contacts as needed. The same as with email notifications, SMS notifications can be edited to have the content required.

To have a contact receive SMS message, you just need to enter their mobile phone on the SMS Phone field for a contact. If this field is empty, contacts won’t receive SMS notifications.

For US/Canada:

For international users, the mobile phone number must be in the same format as if you were dialing an international call

Here’s more information about formatting.