A must have for those with "unlimited incoming calls" mobile plans

In Canada, wireless companies introduced plans with unlimited incoming calls. In many countries incoming calls to mobile phones are paid for by the caller. In both cases generally, making calls from mobile phones is not free and in fact relatively expensive.
A very nice trick to make cheap calls is to use a "callback service". These services call your phone, wait for you to answer, then call the other party.
I've been comparing callback services for a while and the best one I have found so far is Tokiva because it has great call quality and a small program you can install on your phone to initiate the call very easily. It's not perfect (you can only deposit $20, no Paypal, they never answers your email and there is no number to call for support) but relatively it's one the best (for now).
You still need to see if the rates are good for your country. But in North America the rates are great.
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