Iridium extreme ptt User Manual page 49

External Antenna
The External Antenna is designed to allow you to use your phone while
inside an enclosed area in close proximity to an open view of the sky.
The External Antenna screws on to the TNC connector on your Accessory
Adapter. To install, hold the Accessory Adapter's TNC connector in place
while attaching the External Antenna and take care not to twist the wires.
Then attach the Accessory Adapter with connected External Antenna to
your phone and place the External Antenna in an area with a view of the
open sky for use. For the best performance, place the external antenna on
a metal surface (e.g., vehicle roof ) for a proper grounding plane.
The external antenna included with your device is also designed to
operate on non-metallic surfaces.
Iridium Extreme® PTT User Manual 43