Just switched from iphone 6 to a S8, I can use data, make calls, and even receive texts, but I cannot send any. I've put my SIM back into my old Iphone and turned off iMessage and shot a normal text to an iphone used and an android user, they both went through on it. Swapped my SIM back to S8 and still couldn't send texts. I've gone through apples iMessage registry and tried to remove my number from it and it said my number wasn't registered on it. So now I'm back to square one, can anyone help?