The telco’s first move is in the 1,400-metre Arlinger tunnel near Pforzheim (pictured), where five of these wind-resistant signal cones have been installed.

The cones have been designed by Swedish kit-maker Ericsson and are built to survive the high-speed gusts caused by passing cars and trains—something Vodafone says messes with standard antennas.

Vodafone’s network development head Marc Hoelzer said: “ “Closing dead spots in tunnels is particularly challenging for structural reasons alone. Passing cars and trains set large air masses in motion... which can cause vibrations in the antenna technology and thus impair the transmission and reception performance of mobile phone antennas.”

Hoelzer added that the new antennas are “wind-resistant and can support all frequency ranges,” meaning better chances of clinging to a video call or streaming your playlist without it sounding like underwater dial-up.

The plan is to roll out these cone-shaped saviours in another 20 tunnels across Germany. For shallower underpasses, Vodafone reckons entrance and exit antennas often do the trick. But for longer and deeper tunnels—where your signal usually disappears into a black hole—operators use optical amplifiers to carry the mobile signal through a series of antennas and back again without the usual radio silence.

Typically, only one network provider takes point per tunnel to avoid a spaghetti mess of cables, with the rest piggybacking off the infrastructure.