Poor people's use of their mobilephones generates data that leave what can be called adigital footprint. These data are among a handful of sourcesof electronic information that exist on poor people. Thisinformation is potentially powerful but has not yet beenused in ways to radically impact financial access for poorpeople. This brief highlights some early experience on thepotential of digital footprints from mobile phone use. Mostof this initial work is experimental. As long as consumerinterests are protected and privacy, security, and ethicaluse concerns are addressed, these data may become a usefulway to reach unbanked poor people with a range of financial products.