Does Flexfone's Exchange integration support two-step verification?

Yes, Flexfone's integration with Exchange supports two-step verification.

Flexfone's integration with Exchange supports two-step verification, it just requires whitelisting this IP range from Flexfone: 91.217.201.0/24.

Whitelisting IP addresses is an easy solution as it affects all users on the domain at once.

To do this, simply follow the guide from Microsoft, which you can find here.

App Password

Another solution is to create an app password, which can be used instead. However, this solution needs to be done for each individual user.

You can read more about creating app passwords on Microsoft's website.