Due to their low income, 8 million Colombians cannot join the banking system. This means they cannot save or purchase certain essential goods and services. This is why Une created Payphone Bank, an OS that turns Tigo-Une Payphones into micro-saving devices which work like digital-era piggybanks. The objective is to give millions of low-income Colombians the possibility of saving, paying for products and services, and access to micro-loans that allow them to increase their quality of life, build credit history and ultimately join the financial system. We created a software that converts the existing 13,000 Une pay phones across Colombia into de facto digital banking terminals—with no hardware intervention. This feat is made possible by an Asterisk-based Voice Response System that controls the pay phones via DTMF tones. Users can activate an account at any Une store just by showing a photo ID. Then they can navigate the menus though an automated operator. Every coin they insert into an Une pay phone is added to their total balance easily empowering the 8 million unbanked Colombians to join the financial system.