Pros: A good tool as an alternative service, when all the others aren't available or working well, example, your service works better that USTRANSCOM in accessing the Sao Paulo, Brazil, metropolitan area.
Cons: Cannot get connections often, example: 011-55-11-4033-0743 (Brazil-Sao Paulo metropolitan area)
Using 800 number is a little more expensive than your competition (example USTRANSCOM)
You give no option to use a local number at a lower rate to make calls (example USTRANSCOM 718 number which can be accessed from cell phones using excess minutes and cost only .3c/min for a call to Brazil)
Summary: The above is a summary. I have recommended your services to others based on the pros & cons above.