Problem with a malfunctioning GSM modem (connected via Athens).
The RC was initialized, but the SMS could no longer be sent and gradually the modem was completely silent and nothing came out of the monitor port.
When trying to RC restart, a message appeared that rc was already running and in the task manager the rcware.exe process could not be dropped, windows could not be turned off, only restarting the computer with the button helped. The same behavior was observed elsewhere.
However, in the end, another converter was bought, from i-tec, and the modem began to work without problems.
If you encounter the situation described above, the solution is to use another USB-232 converter.