When Daniel Yu was 19 he was living in rural Egypt, in a small town in the Sinai Desert. One day he went to the local pharmacy to pick up Ibuprofen, and saw that the shelves were full of expired medication, or simply out of stock of many crucial treatments.

This scene is not uncommon: according to the World Health Organization, an estimated 40% of health centers in the developing world are stocked out of supplies or medications. In some countries where drugs are needed most, it is common for a patient to walk three days to the nearest clinic, only to find that it does not have the medicine they need.

As an IT professional, Daniel recognized that day what was essentially a systems problem and thought of a solution. Many health providers in developing countries don’t have ready access to computers, the internet or other modern forms of inventory management. But, there is one piece of technology even more common in some villages than running water: cell phones.

Reliefwatch, Daniel’s startup, is a platform for health organizations in the developing world to track medication through mobile phones. The system calls users and asks them to input supply information in the most basic method possible: hitting keys on a number pad. Reliefwatch digitizes the information, integrates it into a cloud system, and then posts it for easy access by warehouse managers charged with resupply.

The system relies on nothing more complicated than flip phones and basic texting capabilities — no Internet access or training required.

Reliefwatch was put to the test recently during a vaccination drive in Uganda to eliminate seven tropical diseases. In past years health centers had run out of essential medication to treat these diseases, but they could not report on their stockouts fast enough to be resupplied in time. Daniel partnered with the country’s Ministry of Health and USAID to streamline communication between health providers and suppliers. By the end of the vaccination drive, there was a reported 88% reduction in stockouts across all districts.

The service is currently being used by pharmacies, government-run health clinics, NGOs and small stores in five countries across Central America and East Africa. Reliefwatch is in talks to partner with USAID in 13 other countries in sub-Saharan Africa, and its product is built to have the capacity capacity to expand to 190 countries at a moment’s notice.

With the success of Reliefwatch, Daniel is developing other products to fill gaps in “last mile information”, or the last step between a product and a consumer. The fundamental problem of stockouts and expired product in the developing world is sector-agnostic. For example, Daniel believes his mobile data system can just as readily help companies interact more efficiently with smallholder farmers who provide cacao, tea or other goods in the global marketplace.

From a headache in the Sinai desert, an idea with global implications was born. Reliefwatch is working toward a world without stockouts, and no matter the market, it has hit on a fundamental problem in need of solution in the developing world.