[Problem] Customers use RTU5020 send SMS command without responding

[Solutions]
(1) Call the equipment to see if it can be connected. If it can be connected and prove that the equipment has a signal, proceed to step two below. If not, proceed to step three below
(2) Confirm whether the SMS command is correct. If it is correct, proceed to the next step. If it is not correct, please check the correct SMS command in the manual

(3) Make sure that the SIM card is installed when the device is shut down, if not, shut down and restart the device, then see if the signal lamp is registered to the signal (judgment method is shown in the instruction)

(4) If the device is registered to the signal, please confirm whether the SIM card in the device has a call charge or whether it has a short message function; if no signal is registered, please proceed to step 5 below;

(5) Please check whether the module version and the card in the device are common. Whether the phone card installed in the device and the module model of the device (2G/3G/4G) are correct.
For example, in China, 2G devices do not support telecom cards, 3G devices do not support mobile cards; 4G devices support full Netcom;
     It is confirmed that the customer is using a 2G device and uses a telecommunication card, so the registration is not signaled.