Telstra experienced a major national service crash on Wednesday morning, disrupting phone services, internet, and train networks.A software defect caused the outage, leaving some customers unable to make emergency calls.Communications Minister Anika Wells confirmed triple-zero call issues affected some users, prompting hundreds of welfare checks.Regional train services in Victoria and NSW faced significant delays, while emergency services were impacted.Telstra resolved the issue by 4pm, blaming time synchronisation problems in Sydney and Melbourne data centres.The company apologised for the disruption, with CEO Michael Ackland stating investigations are ongoing.Opposition critics called for an ACMA inquiry into telco accountability, while the government denied foreign interference claims.The incident highlights ongoing concerns about network reliability and customer service in Australia.