The +CFUN command sets and reads the modem functional mode.v2.0.x
For reference, see 3GPP 27.007 Ch. 8.2.
Set command
The set command sets the functional mode to Minimum functionality, Normal, or Offline mode (Flight mode). There is a specific mode for Flight mode with UICC on. It is also possible to activate or deactivate LTE or GNSS separately.
Read command
The read command reads the current functional mode.
Test command
The test command lists supported functional modes.