Free Calls from Gmail could be misused

I think it's fair to say that while this is an amazing service but then again a lot of people could be misusing this service as well.

For example, many people could start making prank calls or sales calls from other countries to U.S. or Canada. Getting the ability for free calls is only going to give air to such acts which is going to make many people very annoyed.

I think Google should introduce some type of credibility before people can use this service from any gmail account.