The text messages between me and another person keep messing up, my texts would send and say they were delivered but the person would never get them and it works the other way sometimes too, they will send a text but it won't come through, sometimes if I send a text it will trigger the other message to come through but if not then it won't come through at all, this doesn't happen all the time but it happens a lot and I can't work out why, can anyone please tell me a way to fix this please