You NEVER want to call the number back. Just because it's a US area code, doesn't mean when you call the number back that that's where you're calling. You could end up being charged a ridiculous amount of money straight to your phone bill. Best thing to do is block the number or area code if the area code isn't local to you
They called several times times. This last time they asked to confirm my business address. I asked who was calling, they said Chamber of Commerce. I advised I would need to give them a different number, they hung up.
Have called a couple of times, no one there. 3rd time answered, they asked to confirm business address. I did, then wanted to know who owned the company. I asked who they were. He said American Chamber of Commerce. They were updating their files. Told him I would not give him any more information. He was calling from Omaha, Nebraska.