I have an N900W8 note 3 and recently out of nowhere I started to get a message saying "Not registered on network" every time I try to make a call. The strange thing is that it only happens in some places, as if it were a problem with signal, but i always get at least 3 bars. I don't think it´s a problem with imei because every now and then i can make and recieve calls when I´m in certain places in the city. I have it rooted running android 4.4.2, the problem began before I updated it when I had 4.3. Its running stock touchwiz rom, and I already tried doing a factory reset to no avail. I also tried changing the network mode to 3g, GSM, and manually registering on the network (Telcel) but it still gives me the Not registerd on network message..... Any help?