Calling NVC

Since I received the hard copy of the approval noticed(NOA2) in the mail on May 18, I've been started calling everyday but I was no luck. This morning I called NVC automated voice response system and as usual I followed the prompt voice instruction, to my surprised a case number has been generated on May 25. So I wrote down my mother's MNL case number . After I hanged up I called again and spoke to an operator. The lady asked my information and my mom as the beneficiary. Then my email was verified so as my mom. So all correspondents from the Department of State will be sent to both our email addresses. I am also waiting for the AOS bill that they are going to send me. As soon as I get it I will pay it online right away so there's no delay.