(01) Please pay attention to the orientation when inserting the SIM card. If you put the SIM card in the wrong direction, the deck can still lock it like a Micro SD card (a click is heard) but it wont work properly and you will not have a 4G LTE signal on the notification bar.
(02) The SIM card should be inserted before head unit is powered up, otherwise, the system won't recognize it and you have to do a circuit reset using<Reset>hole on the front panel in order to get it to work properly.
(03) SIM cards issued by some operators are locked (or protected) by a PIN code, and the PIN code can be found on the SIM card carrier. In this case, you need to put this SIM card in a phone to manually disable (or unlock) the PIN code before putting it in the headunit.
(04）Please go to Settings- Wlan-More-VPN(Some mobile operators require APN configuration for network to work).