Actually, Mubble gives per second rate first time but then our system learns on its own after you make minimum 5 calls.

We realize that it needs to work better. So we will keep improving the automatic rate detector with every release.

If operator doesn't sent pop-up after call, we estimate call charges using call rate which sometimes may be wrong. Don't worry, It will get automatically correct after few calls. Please refresh your balance to get current balance.