IPhone4S Unicom mobile phone iOS7.0.3 can't send short messages!

I suggest you check whether you have chosen the wrong firmware when upgrading the iPhone4s. This problem may occur if you select the wrong firmware version. At the same time, if you are an American version of the iPhone, some of it is locked, and you should use a card after unlocking it. After the upgrade, if the card stickers don't match, this situation may also occur, and you need to use a matching card sticker. If there is a problem with the upgrade, you should also go to the local after-sales inspection.