This is who answers when you call the number back:
Broadridge Proxy Service Centers.
From their website:
Broadridge is a leading global provider of technology solutions to the financial services industry. Our systems and services include investor communication solutions, and securities processing and operations outsourcing solutions.
Global Headquarters:
5 Dakota Drive, Suite 300
Lake Success
NY 11042
If you've never done business with them, then I suggest you file a Do Not Call complaint with either the National or your state Do Not Call.