ZTE V880 Unicom contract machine can't send SMS, just change your mobile phone, what's the problem! thank you

1. Don't owe the mobile phone card. 2. Have you sent many short messages before? If so, it is possible that the short message function has been turned off by the operator, and this short message is completely invalid. You need to call 100 1 1 to find a manual customer service to help you open it before you can continue sending it. 3. If the above 1, 2 is not true, is the mobile phone setting changed? You can consult 100 1 1 to tell you the correct SMS center number, and you can change it back. 4, that is, whether the mobile phone information reaches the upper limit, delete some unnecessary information. 5. There is something wrong with the mobile phone.