We're happy to inform you that ALL CARRIERS are now compatible with RoboKiller in the US and Canada. A couple of notes, though:
First, please, make sure your carrier and pricing plan both support call forwarding. Some carriers (MetroPCS, C-Spire, etc.) may not have the call forwarding feature included in your plan by default. The app will work best with busy, unanswered, and unreachable calls forwarded only, but if your carrier can only forward (or not) all of your calls, - that's OK too. The app needs any call forwarding to work.
Also, please note that only devices with iOS 13 and above will have access to the Call Screening feature.