@TTCJ, sure. To be clear, I reached out to USCIS, was trying to confirm whether or not my petition had been sent to NVC by USCIS. It is my understanding that you want to call NVC not USCIS to inquire NVC case number. So I need to confirm beforehand that NVC has my case before I contact them for case number.
First things first, you want to make sure that you're reaching them out during normal business hours, Mon thru Fri 8 am to 8pm EST. I chatted at around 9 am. I went to USCIS website. There's little chat box that says ..Need Help? Ask Emma. I clicked it and typed in Has my case been sent to NVC?
Emma (bot) then would list some suggestions but at the end of the list there's an option for Live Chat with representative. I chose that option. It asked for my case number and less than a minute later I was connected to a live agent.
Usual drill, she asked for name, address, phone, email to verify. I explained what I was looking for. At first she gave me generic answer saying that on 9/26/2022 my petition has been approved and that I should expect to get the approval letter by 10/14/2022 etc etc. Basically the same information we got from the approval letter. But then I reiterated that I already had that information and that I was reaching out to get confirmation from her (USCIS) that my petition had indeed been sent to NVC and on what date. I also explained to her that she should be able to look it up in the system as many people did manage to get this information from USCIS. About 3 mins later she confirmed that my case had not yet been sent to NVC. I asked whether there's a time frame we could expect it to be sent to NVC. She answered that there's no timeframe that she knew of unfortunately, she could only say that it may take 90 days for me to receive something from NVC.
My plan is to reach them out weekly. I will most likely do it in chat since to me it seems to be more intuitive to get to a live rep than calling, it's more convenient and faster too. Again, my own personal opinion. I do get that some people are more comfortable talking directly with customer service.
G'luck!