[Matt3o12_]

Are you willing to make international users pay up to 80¢ per verification? If someone cancels a call, I still have to pay for one minute (it's only free if I cancel the call). So if I were to call any American number that hung up on me, I have to pay 80¢ (USD dollar cents of course).

Just pay the 0.02¢ or whatever phone services charge these days. If your business is actually big enough to have to worry about phone verification, do it right. Users don't like to call your number since they don't know the costs associated with it (especially international users). Furthermore, it makes number spoofing much harder.