Mobile health interventions are an innovative way to improve health outcomes and may play a powerful role in mitigating health disparities. However, their use poses special challenges and few articles have reported specifically on digital technology interventions for vulnerable populations. This article shares our experience from the Tika Vaani ("vaccine voice") Intervention which uses a combined face-to-face and mHealth strategy to educate and empower beneficiaries to improve immunization uptake and child health for a poor, low-literate population in rural Uttar Pradesh, India. Based on the mERA checklist, a guide to improve the completeness of reporting mHealth interventions, we provide information about the process of development, implementation and lessons for scaling up the Tika Vaani intervention. This study contributes to the literature to improve reporting on mHealth interventions and provide researchers with key points and actions to take during intervention development to serve hard-to-reach communities and improve health outcomes. CCS CONCEPTS • Human-centered computing~Interaction design • Humancentered computing~Human computer interaction (HCI)