Techcrunch reports of a free online website that allows its users to enter a phone number and call it for a specified number of times automatically. They haven’t mentioned the website name but since the webmaster has posted his email address in the comments, it is but a child’s play to find out the website from the email address domain which is http://phonemyphone.com/

Currently you can make calls only to the US but international calling is coming soon.
On the website, the owner states that the IP Address is logged and can be used to cooperate with law enforcement agencies. But again, with all the multi chained proxies available, it is not going to help the prevent any misuse of the service.