What is grandcentral.com?

Tweet

Okay, I had checked out this website called "Grandcentral.com". You can sign up for free I guess. But how does it work, there wasn't much description on the homepage there. They only explained that to assign one number to all of your cellphones. You can receive calls internationally, and also text for free. Later on, grandcentral also will be go direct to Google voice. I just want to know how does grand central work. Has anyone signed up with it?