ISDN and POTS Telephony at Congress and Camp

Explore the volunteer-driven deployment of legacy ISDN and POTS telephony networks at CCC events through this 36-minute conference talk from 39C3. Learn how a dedicated group of volunteers recreates authentic digital and analog telephone services using decommissioned telecom hardware rather than modern VoIP solutions. Discover the technical implementation involving actual legacy equipment including Siemens EWSD digital telephone exchanges, Nokia EKSOS V5 access multiplexers, and SDH rings for E1 carrier transport. Understand how attendees can access subscriber lines for various services including traditional telephony, fax machines, modem dial-up to BBSs, dial-up internet access, and video telephony. Examine the broader mission of preserving early digital communications infrastructure from the 1970s-1990s and its operation methods, including contributions to communications museum collections. Gain insights into the network hierarchy construction, equipment specifications, operational services, lessons learned from deployment, and newly-developed open source software for interfacing with retro telecommunications gear. Presented by Harald "LaF0rge" Welte, this talk demonstrates how these temporary event networks serve both as technical achievements and important preservation efforts for digital communications heritage.