What is essential for the operation of satellite phones?

A clear view to the sky is essential for the operation of satellite phones because these devices communicate directly with satellites orbiting the Earth. Unlike traditional mobile phones that rely on ground-based cell towers, satellite phones require an unobstructed line of sight to the sky to establish and maintain a connection. This direct visibility allows the phone to send and receive signals effectively, as the satellite must be able to "see" the phone and vice versa. If there are obstructions, such as buildings, trees, or mountains, the signal may be blocked, resulting in poor connectivity or complete inability to make calls.

In contrast, the other options do not apply to satellite phones. A loudspeaker is not necessary for the functionality of the phone itself; it can aid in call quality but is not essential for operation. Some may think strong local network coverage is vital, but satellite phones operate independently of local telecommunications infrastructure. An internet connection is also not required for their basic functionality, as they primarily handle voice communication and SMS rather than relying on data services.