Can etCare Sue Me?

I had an account with Bally's that should have been removed. Long story. I recieved a call from etCare and the guy told me that they are suing me for the $1200. He told me an address that is not my address and i told him that it was wrong but would not give him my current address. he told me that I can check with the court to see that a suit has been filed. I thought that debt collection companies can not sue you and that it is illegal for them to threaten that.