This thesis explores how service design can guide the safe integration of large language models into crisis lines and first-contact mental health teleservices. Based on research with In Touch Community Services, it proposes the Responder’s Notebook, a responder-facing prototype that supports pre-shift readiness, quiet reference, documentation scaffolding, and reflection while keeping crisis care human-led. The work is supported by a service blueprint and AI Use Decision Framework that clarify boundaries, safeguards, and organizational decision-making.