Linkpearls and their capabilities.

[Grayve]

Actually, link pearls are two way radios. Cid starts to explain how they work via electromagnetic signals at one point, and when the warrior of light just stare at him, he sighs and says it works via aether.

Possibly Meaning that the link shells are garlean tech. This also means they may not be that wide spread. We still see runners being used, for instance.