While there is a strong imperative to deploy necessary broadband infrastructure to provide Internet services in rural and remote areas, this must be undertaken in a sustainable and cost-efficient way. Indeed, it is essential to carefully minimize energy consumption, associated emissions, and investment costs in universal broadband strategies. Infrastructure sharing can help achieve this. Thus, a theoretical method is developed to quantify the energy, emissions and cost impacts of universal mobile broadband, consequently applied to developing Asia. The results find that to deliver 4G of 20 GB/Month per user (via a wireless backhaul) the operational CO2eq. emissions reach 88.9 Mt annually in total, or between 16 and 37 kg per smartphone for different country income groups. Importantly, infrastructure sharing strategies can lead to energy and emissions reductions of 9–19 %, as well as reduce necessary financial investments by 15–49 %. Policy choices to encourage infrastructure sharing can consequently enable substantial reductions in energy consumption, emissions and costs.