Just want to share my experience for calling USCIS to check the NC status:
1. Use POJ method. Here is the link how to:
http://web.wenxuecity.com/BBSView.php?SubID=immigration&MsgID=364066
2. Keep calling until you reach a customer Rep, it might be a rep or an IO. It’s no use to speak with a rep, they cannot access your case from the system. If you are lucky to reach a NICE IO who is willing to help you, here are the questions he need to assistant you for status inquiry.
2.1 Your Name…
2.2 Your Case#, case type ( We only care I-485…)
2.3 Your DOB ( Date of Birth)
With this info, they can locate your case status from the system.
Good luck!