Well they recon after a hands on that's the SIM card slot and only the ad slot is inside.
http://www.tomshardware.com/news/nokia-lumia-920-lumia-820-windows-phone-8-phone,17438.html
http://www.tomshardware.com/news/nokia-lumia-920-lumia-820-windows-phone-8-phone,17438.html
Button and connector layout is similar to the 920, except the 820's microSIM slot is at the bottom of the phone, next to the microUSB port. In our opinion, it would be more convenient if the microSIM and microSD card slots could switch places so the memory card is accessible without removing the shell and battery.