We have used Duo for quite a while with Citrix Netscaler and our users prefer the callback option. This option disappeared suddenly on Friday (as far as we know, it could have been Thursday). Was this option removed or moved to a paid plan (our users use telephony credits)? Do I need to update a config somewhere? I didn’t set this up and the guy that did passed away and left no documentation, so I’m a bit lost on where to go.