DOCoSPADEo said: c'mon, it's the 21st century. It's gotta be a cordless landline phone.
With Chireiden being near a whole goddamn nuclear reactor, I'm sure a cordless subterranean phone line is nothing. Hell, you have limitless solar, thermal, geoth...never mind that, nuclear fission, nuclear fusion, radioactive decay and all that. And what's even better, the source of it all is YOUR PET!