What is the matter that the GPS locator can't be turned on remotely?

The GPS locator can remotely control the switch of the equipment by sending instructions through short messages, but we can't control it remotely at all times, and the main reasons why the locator can't be turned on remotely are as follows:

First, the positioner is powered off.

Second, the locator can't receive the signal.

Third, the SIM card of the device does not have SMS service.

Fourth, the SIM card stores too many short messages.

Five, the instruction error

It is suggested to examine the problem according to these five points.