Marketing Cloud How to preview SMS?

When I try to select a contact to preview SMS, there’s no available data extension showing up.
How to preview the SMS?

Step to preview SMS content with data extension

In order to preview the SMS with the selected contact, the key is to add the field Locale with type Locale into your data extension.

Here are the steps:

1. Add Locale to your data extension with type Locale. (key steps)

2. Browse to your SMS Subscriber preview mode, you can find the data extension showing up. You now can choose a contact and preview the SMS content.