1) Make sure the SIM card is inserted correctly into the watch. Check to see if 4G, 3G or 2G is displayed on the top left of the screen of your watch.
2) If not, long press the Power key for 15s to restart the watch.
3) If 4G, 3G or 2G is displayed, check to make sure there are no overdue network charges that need to be paid.
4) Check if the watch is connected to the cellular network.
5) Check if the watch is in arrears.