If you're using a Macintosh, you should be able to check supplies by going to System Preferences > Print and Fax > Options and Supplies > Supplies Level. If you're using Windows operating system, there's no other way to check it unless the printer is on the network. It can be seen by accessing the embedded web server(EWS) page. To access EWS, go to Control Panel > Printers/ Printers and Faxes. You should see something like this:
You need to look for the IP address of the printer. On the image, it's the one that says http://10.194.200.217. After getting the IP address, open internet browser (e.g. Internet Explorer) and type the IP address in the address bar as shown:
After typing the IP address in the address bar and hitting "Enter" on the keyboard, you should see the EWS page with the supplies level. Otherwise you need to have OP panel serviced to check supplies. Hope this helps. If you need more assistance, leave a comment and I'll get back to it. Thanks.