Why can't Guangdong Unicom mobile phone users exchange prepaid cards through SMS?

Guangdong Unicom mobile phone users can't redeem recharge card points through SMS, which may be due to the following reasons: 1. The status of the user number is abnormal, such as arrears, downtime or blacklisting of the user; 2. The redemption and adjustment of points have not been completed; 3. It can be redeemed 1 time per month, subject to the success of the first SMS application, and other SMS applications in that month are invalid; 4. The billing date of the system is 1-5 every month, and the system is too busy to accept and undertake. You can start this business on the 6th of every month.