No AT command parser available after AT+CFUN=0

The -C1 models do not take AT commands after processing a AT+CFUN=0 command. The -C models did allow AT commands after the AT+CFUN=0.

An example of a usage that used to work with the -C models that no longer will work with -C1, was to read and delete stored SMS's after the AT+CFUN=0 (as a way to prevent more SMS from being received during this operation).

With -C1 models a hardware reset or power cycle must be performed to restart the AT command parser after AT+CFUN=0 is issued.