may tinh minh bi loi vietkey ae thong cam. minh moi thay doi goi luu luong sim line tu 3g len 6g , bay gio minh nhan sim rui. nhung lap vao may thi chi co song 3g. khong len dc song 4g. minh da thu cai lai het apn cac kieu ma ko dc. ai da tung lam rui giai dap giup minh voi