The device is managed by SMS or call. You pay for the incoming SMS or call according to the tariffs of your operator. In most cases it is free. The device sends SMS’s to you - you will pay for these messages according to the tariffs of your operator. You can also configure the device so that it does not send confirmation messages and therefore does not reduce the credit of the installed SIM card. Some operations, e.g. rebooting or switching, can be configured to operate for free.