said by NickDishman:With US credit cards there is no sale's tax included.
The supplied localphone.com softphone does not allow any choice of audio device. (But it is possible to use a third-party softphone such as X-Lite).
If you pay in Euros or UK Pounds, adding a credit of 5 units will cost you up to 6, depending on the VAT rate at your Credit card address. I don't know if you pay in USD if Sales tax applies.
Also, all the time of a call seems to be charged for, even if the other party does not answer.