I'll give you a generalised answer, but I am not familiar with the app called Signal.

As I understand it, signal is an app that has versions for Android and IOS, it's an app not an operating system so it will use the TCP/IP services provided by the operating system upon which it sits. So, unless the device has satellite connectivity, it will not be able to communicate other than via whatever the device provides.

or more simply, it is the device (phone or terminal etc) that communicates with the satellites and the app (signal) will use the network provided by the device. Specific hardware is needed and Signal is not hardware.

I'll give you a generalised answer, but I am not familiar with the app called Signal.

As I understand it, signal is an app that has versions for Android and IOS, it's an app not an operating system so it will use the TCP/IP services provided by the operating syetem upon which it sits. So, unless the device has satellite connectivity, it will not be able to communicate other than via whatever the device provides.

or more simply, it is the device (phone or terminal etc) that communicates with the satellites and the app (signal) will use the network provided by the device. Specific hardware is needed and Signal is not hardware.

I'll give you a generalised answer, but I am not familiar with the app called Signal.

As I understand it, signal is an app that has versions for Android and IOS, it's an app not an operating system so it will use the TCP/IP services provided by the operating syetem upon which it sits. So, unless the device has satellite connectivity, it will not be able to communicate other than via whatever the device provides.