The reason why we have $30 is our margin on VOIP is very low. Whenever we do a transaction our payment gateway (stripe-which is the best) charges us a flat 30 cents for any transaction irrespective of the amount + the transaction fees. If we reduce the min balance to $10, at 30 cents 3% will be given to the payment gateway in a business that already has only 15% margin. A lot of companies charge additional transaction fees which are hidden in FAQ and Terms.
Example- https://monosnap.com/file/frAgIDe1kwacNvlp2dnSbRFp78gLfR .We did not want to put the 3% somewhere hidden in FAQ, decided to include it in our cost and hence has to go min $30 of credit purchase.
To further protect our users, we have lifetime validity of calling credits+ remaining credit can be refunded at any point if you don’t us.