A GSM modem with a MegaFon SIM is connected to the computer (Debian), I am trying to send a message using AT commands
ATE1 OK AT+CPIN? +CPIN: READY OK AT+COPS? +COPS: 0 OK AT+CSCA? +CSCA: "89262909090",129 OK AT+CMGF=1 OK AT+CMGS="89169478466" > qwerty +CMS ERROR: 500 After entering the message and pressing Ctrl+Z an error +CMS ERROR: 500 appears, I cannot understand why and how to fix it (there is money on the SIM card, the card is registered on the network, since there is an Internet connection)
