Hello, I have an ipad 4 4G and my cellular function is completely disabled: on the top left corner it only says ipad and shows my wifi signal (it should say no sim), in the settings menu there is no cellular option, and in the about section of the settings i don't have the IMEI. Practically my ipad behaves like is only wifi (it has the sim tray and i have checked the serial on the web: it's 4G). Also, i get the "An error occured during activation" message when i try to use imessage and facetime, but on my iphone I receive the message that this apps are now used on an ipad. I have restored the device several times, even with a sim inserted and updated to ios 8.2 with no success. I have also called apple support, but they came with no good idea to resolve my issue, maybe someone here is better then them☺️. Can anyone help me with advices on how to resolve this? Other then this, the ipad works flawless. P.S my ipad doesn't have warranty so the services I have contacted offered only to replace it at absurd prices. Thank you in advance for your thoughts.