My Sprint Galaxy S8 has been doing this for about a week now, very frustrating stuff. I use the stock messaging app. Everytime I'm texting now, when I go over 160 characters it turns the message from SMS to MMS. I usually wouldn't have a problem with this, but my girlfriend has data caps, and when she goes over data, she cant recieve my texts when they're sent mms. I used to be able to send about 7 text blocks before it would convert to mms, and now even if the message is 161 characters it will be sent as mms. Please help me. I've been trying to find a solution all night and nothing so far has lead to a solution.