Question: In a Mobile Application Part (MAP) context, what does the 'Calling Number' parameter primarily represent?
Option 1: The number of the mobile subscriber being called.
Option 2: The calling party's number, initiating a communication.
Option 3: The address of a Short Message Service Centre.
Option 4: The originally dialled number to reach a different network.
Explanation: In the context of MAP, the 'Calling Number' parameter identifies the calling party initiating the communication, crucial for call setup, billing, and other processes. Option 2 correctly reflects this definition.