Def Con's much-loved Ninja Badge game has become a staple of the world-famous hacker convention, taking place this weekend in Las Vegas. In the past, the hackable circuit board badges acted as invitations to Def Con's annual VIP Ninja Party, allowing guests to socialize and earn points and virtual items by "attacking" others in close proximity. This year, the team of volunteers behind the game have taken it several steps further: they've built Ninja Tel, their own pirate cell phone network that runs out of a van parked inside the Rio's convention center.

The project starts with a small army of special HTC One V Android phones being distributed to 650 lucky attendees and staff members (and yes, NSA agents) at this year's Def Con. But rather than simply have these phones perform all of their usual functions, the custom ROM allows for an experience tailored to the social aspects of Def Con.

Everyone with a phone is assigned a number unique to Ninja's short-range network, and everyone on the network is visible to everyone else. The network is limited to voice and SMS only, but the phones' custom ROM allows for some special functions, like peer-to-peer communications, an in-network voice chat room service, and even an app that orders soda or beer from special Ninja vending machines.

"It's all about creating a platform and then seeing the unexpected things that happen"

What you wind up seeing as a result, the creators say, is spontaneous communications — a kind of throwback to the days of local telephone directories. "It's all about creating a platform and then seeing the unexpected things that happen," says John Hering, one of the Ninja project's contributors. But despite the focused social experience, the firmware is still hackable as ever, and even allows Ninja "subscribers" to build their own apps within the ROM. "We're particularly excited about what's actually going to happen with the platform over the next 48 hours," says Hering.

Behind all of this is Ninja Tel's mobile broadcast station, which got its legs when a Def Con attendee ripped a door from a telco van and brought it to a previous conference. "They brought it back this year, but with an entire van," says Dave Clements, another Def Con staff member who introduced us to the people behind the Ninja project. Cstone, an engineer for the project, showed us the van's interior, which closely resembles a command center with constellations of blinkenlights emanating from stacks of networking equipment, and wall-mounted computer monitors showing real-time network activity.

The project will culminate at this year's Ninja party on Saturday night, which Ninja team members say will be the project's final outing at Def Con.