GDI or Global Domains International is not a scam. Here is how to cancel your account from the FAQ section of their website. I have called the number in the past and have gotten excellent service. Members of GDI have successfully been making money for a few years now. When you sign up, you select a domain name. If you read the site carefully (and it is available in many languages) you will understand the process and how it works. The phone number is a valid number. They will call you to welcome you to GDI when you sign up for your free 7 day trial. After the free 7 day trial, you are expected to pay $10 per month for your domain name or cancel your account if you don't wish to continue.
How can I cancel my account in full?
For security purposes, all cancellations must be completed by telephone; no exceptions. You can reach the cancellation support department by calling (760) 602-3000 and choosing the appropriate menu option between Monday and Friday from 8-5 Pacific Time, and we will gladly assist you. Alternate methods of cancellation will not be accepted.