Just to be clear, this is not a clever mod made to act like a cellphone. It is not a plugin that mimics what a phone can do in-game between players. This is an actual, working phone plugin, that can connect with real cell towers. It can send photos to real phones. It can voice- and video-chat with real phones. It is, for all intents and purposes, a real phone in-game.
Sethbling and Verizon teamed up to bring the unthinkable into Minecraft, and the results are insane. At first, it almost seems like some kind of elaborate hoax, but verizoncraft is real, it works, and as the video above shows, it is crazy. Seth is able to surf the web (albeit at an incredibly low resolution), have a real-time video chat with Captain Sparklez, and even send an in-game selfie to his real-world phone.
It's pretty remarkable to watch, but if you are code-savvy and want to try this yourself, Verizon has provided open-source examples of how verizoncraft works, and you can see it first-hand!