Say you’re at a big event, if the Eventphone DECT phone system is in place, just bring a compatible DECT cordless phone that conforms to the GAP standard and register it to DECT. If you have no such phone, you can buy one for 15 euros.
Then you can use the phone to make internal calls to any other extension for free. No more crazy double roaming charges just to find your friends.
The system is professional and boasts a huge internal call capability. Your extension can also be reached from the outside. By now Eventphone has become a part of the basic infrastructure of any large-scale European hacker event and currently the system is being used at What the Hack.
Via The Lunatic Fringe.