+CNUM may return ERROR when the modem fails to read the own numbers from the SIM card or when the SIM card hasn't been activated. Use $NWMDN to read the MDN as a fallback, which distinguishes these two cases.
+CNUM may return ERROR when the modem fails to read the own numbers from the SIM card or when the SIM card hasn't been activated. Use $NWMDN to read the MDN as a fallback, which distinguishes these two cases.