Although Ooma support states that their Mobile app will work on Android phones, including the Amazon Fire phone, the fact of the matter is that one needs the Google Play app installed before one can download/install the Mobile app, and the Google Play app is NOT compatible with the Fire phone or any Kindle device. The Fire phone may be Android, but it has the Fire OS running on it. I've just spent a few hours mucking around with this, including phone calls with Ooma and Amazon support. It would be good if Ooma developed a compatible app and made it available in the Amazon AppStore.
I didn't find the right solution from the internet.