OpenVPN 2FA SMS only

[jldts]

Hey, community!

I'm looking for a way to implement OpenVPN 2FA without an app, only SMS codes. I know this is a security risk, but my users do not want to use their personal phones for any apps. The setup for DUO is completed, but the only wait with DUO is to use the app or to obtain temporary passcodes.

Is there a solution or way to go about it?

I appreciate any advice.

Thanks.