Input (grade 13): Connectivity to the fixed network (which may be of many different kinds) is done through a base station or "Radio Fixed Part" to terminate the radio link, and a gateway to connect calls to the fixed network.
Output (grade 8): The communication with the fixed network is done through a base station which is called "Radio Fixed Part", and terminates the radio waves. The base station then uses a gateway to connect the calls to the fixed network.