You can only check the case status by either calling the automated voice response system or email them.
The automated voice response system is available 24/7 and as long as you don't have a NVC case # your CIS receipt number will do nicely

If your petition hasn't been approved yet/hasn't made it to the NVC you'll hear that they have no record of your case.
On weekdays from 730am/midnight you can call and talk to an operator.
Email:
NVCINQUIRY@state.govQUOTE(natashenika @ Jun 24 2007, 12:20 PM)

one more
can I check the case status in NVC the same way i can on usics web? if so what is the link for that or the only way is to call there???