A wireless power transfer system includes a power transmitter configured to provide a power transfer to a power receiver via a power transfer signal. The power receiver includes a first mode controller configured to transmit a standby mode exit request to the power transmitter by changing a loading of a communication inductor of the power transmitter. The power transmitter includes a mode controller configured to control the power transmitter to operate in a standby mode where a presence of the power receiver is detected but no power transfer signal is generated. A detector is configured to detect an impedance change of the communication inductor. The mode controller is configured to initiate a transition from the standby mode to a power transfer mode in response to the detector detecting the impedance change.