Purchasing credits is easy and the more you purchase, the lower the cost per page. For example, sending a fax in the United States uses 11 credits per page. Purchasing the 2000 credit package will cost you only 27 cents per page compared to 58 cents per page if you purchase the 75 credit package.
Number of credits / Cost for the US customers (may be different for the non-US customers, based on the Apple AppStore price tiers)
75 credits - $3.99
200 credits - $9.99
600 credits - $19.99
2000 credits - $49.99