Ending the analogue telephony era

2024 marks not just CERN’s 70 th birthday but also the end of analogue telephony at the laboratory. Traditional phone exchanges and the associated copper cabling cannot deliver 21st-century communication services and a decade-long project to modernize CERN’s telephony infrastructure was completed earlier this year. We report here on CERN’s modern fixed telephony infrastructure, firstly our inhouse development of an exchange which, based on open-source components and standard VoIP protocols, supports softphones, call centres, safety communications, interconnections with other voice services and an automatic switchboard, and secondly the two CERNphone applications that have replaced fixed phones, and which are used by more than 6000 users each week.