Telecross REDi heatwave service delivers daily phone check-ins to elderly, isolated, and health-compromised individuals during extreme heat events. Triggered by heat alerts from meteorological authorities, trained volunteers assess wellbeing, share heat safety advice, and initiate emergency responses if needed. The service uses data-driven tools to identify high-risk areas and prioritize outreach, ensuring resources are directed where most needed. Volunteers are equipped with guidelines for identifying heat stress and are supported by escalation protocols involving emergency services if clients do not respond or report symptoms. Operating each summer season, the program adapts to prolonged heat periods and is backed by strong privacy safeguards and continuous evaluation. It enhances personal safety while reducing pressure on emergency systems. With strong interagency collaboration and a foundation in community trust, Telecross REDi exemplifies a scalable model for climate resilience through personalized, low-tech interventions that strengthen public health infrastructure in the face of rising heat extremes.