[Question]: The mobile SIM card installed in the device can always send SMS messages when the alarm is issued. After a period of time, suddenly it is impossible to send a SMS message. What happened? (The device's signal light is flashing at the frequency of normal registration to the signal)

【answer】:
(1) Please check if your mobile phone card is in arrears;
(2) Please check if the SMS function of the mobile phone card is restricted. Put the phone card into the phone to test whether it can send and receive SMS messages normally.

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