Aporte original por: Hikary Katsu ,
Take out the simcard and clean it with microfiber if you have that (don't try enything else). If that doesn't work,try calling someone and/or go to call settings and change Preferred Network between Global, LTE , GSM, CDMA, UMTS(depends where you're from) . Try it in a different phone if you can. If neither of these worked the problem is most likely the sim card.