This study evaluates a project led by On Cue, a small company based in Cape Town, South Africa, which sends SMS messages to patients via mobile telephones, reminding them to take their tuberculosis (TB) medication at pre-determined times. This service aims to provide an affordable solution to improve patient adherence to TB treatment and reduce the associated costs of the directly observed therapy system for both patients and clinics. This report presents the lessons learned so far, as well as other uses of cellular technology in the healthcare sector.