How did the 1926 Hamburg-Berlin train phone work?

Question

Accepted Answer

It used wires strung parallel to the railway tracks as antennas to maintain a continuous connection.
This was the first telephone installed on a moving train. But it wasn't truly wireless in the way we think of mobile today. The system relied on inductive coupling between the train and wires running alongside the tracks. The train essentially "followed" the antenna.
Why this matters for mobile history: It reveals the core challenge that would define the next 50 years of mobile communication: how do you maintain a connection with something that moves? The train solution was clever but limited to a fixed route. True mobile networks needed a completely different approach: the cellular concept, which wouldn't arrive until the late 1970s.
Go deeper:

Basic Cellular System Concept (Electronics Notes) — the answer to "how do you stay connected while moving": dividing coverage into cells with handover, instead of a fixed wire along the track.