The Touchstone rear panel includes a secondary induction coil.

The magnetic field generated by the base unit turns on and off rapidly, generating a magnetic pulse that is carefully tuned to the dimensions of the wire coil inside the phone. This oscillating magnetic field induces a current inside the phone, allowing the battery to be charged.

Similar technology is used to transmit power to some battery-operated toothbrushes, razors, etc.

This explanation is an oversimplification of a very specific field of electrical engineering.

You'll note that the location of the induction coil is in the center of the device, well away from the antennas that line the perimeter of the phone.