In Bangladesh, over one-quarter population live in urban areas. About a third of this population live in slums. Poor nutritional status and above-average under-5 mortality are major concerns in urban slums. Immunization coverage is markedly lower in urban slums (67.5%) when compared to the national estimate (82.3%) of Bangladesh. Previous research has determined that the main reasons for low coverage in those areas are absence of an effective mechanism in tracking newborn children and reminding parents about EPI sessions. Evidence here and in other low-income countries has shown the use of mobile phones to be effective and acceptable for marginalized populations, and this new technology-based approach contributed substantially in improving vaccination coverage. Our proven innovation as mentioned below will be scaled up with the aim to successfully vaccinate all male and female child populations in highly mobile populations in order to achieve the targets of Sustainable Development Goals (SDGs). In our pilot study, a very low cost application was employed within the existing health system to register birth of every child electronically and auto remind mothers about routine vaccination dates with text messages. Android Smart phones were provided to all vaccinators and their supervisors in the study sites. The intervention package included: (i) mobile phone-based registration of pregnant women and children, (ii) birth notification by mothers/clients, (iii) system for auto reminders to clients, (iv) system for auto reminders to vaccinators, (v) mobile- and web-based monitoring of performance by supervisors. The very low cost interventions were implemented through the existing health system–the Expanded Program on Immunization (EPI)–run by Ministry of Health (MOH). The pilot study demonstrated significant improvement in childhood vaccination coverage among children living in hard-to-reach areas and urban streets after implementation of the innovative system. The intervention package is now positioned for scale up and the scale up will be done among the urban slum (highly mobile) populations in Bangladesh. Scaling up of above mentioned successful intervention package will lead to increased prevention of vaccine- preventable diseases among both male and female children living in urban slums. More details about the questions are provided with my submission.