> 3.2.5 | Power Management

> The modules support various power saving modes. These can be configured with the AT+CFUN command alone as long as there is no active USB connection. For details on how to configure power saving with AT+CFUN see [2].
> However, if the PC host application employs the USB interface, power saving must be configured both on the module and on the PC host, i.e. the PC host must be set to suspend mode (usually Selective or Global Suspend) by the PC host's power management system. The PC host's power management system (e.g., ACPI = Advanced Configuration and Power Interface management system) has to be configured to support power saving for the USB port the modem device is located at.
> If you modify the AT+CFUN parameters only, the selected <fun> level is accepted, but the active USB connection keeps the module alive and thus prevents power saving until the USB plug is disconnected. Also, if the module is in SLEEP mode, reopening the USB connection will cause the module to stop power saving although the configured CFUN level did not change.
> A major feature of the module's USB functionality in connection with the PC host's power management system is USB Remote Wake-up. With this feature it is possible for the USB modem device to wake up the USB host controller from any sleeping state. Reasons for a remote wake up could be: An incoming call (RING) indication or some other important message, i.e., Unsolicited Result Code (URC). In these cases the USB modem device wakes up the USB PC host and the signal or message may for instance be displayed on a terminal application.