Ten lessons learnt: scaling and transitioning one of the largest mobile health communication programmes in the world to a national government.

There has been exponential growth in the numbers of 'digital development' programmes seeking to leverage technology to solve systemic challenges. However, despite promising results and a shift from pilots to scale-ups, many have failed to realise their full potential. This paper reflects on lessons learnt from scaling and transitioning one of the largest mobile health programmes in the world to the Indian government. The complementary suite of services was designed by BBC Media Action to strengthen families' reproductive, maternal, neonatal and child health behaviours. Mobile Academy was a training course to refresh frontline health workers' (FLHWs) knowledge and improve their interpersonal communication skills. Mobile was a job aid to support FLHWs' interactions with families. delivered weekly audio information to families' phones to reinforce FLHWs' counselling. As of April 2019, when Mobile Academy and were transitioned to the government, 206 000 FLHWs had graduated and had reached 10 million subscribers. Lessons learnt include the following: (1) private sector business models are challenging in low-resource settings; (2) you may pilot 'apples' but scale 'oranges'; (3) trade-offs are required between ideal solution design and affordability; (4) programme components should be reassessed before scaling; (5) operational viability at scale is a prerequisite for sustainability; (6) consider the true cost of open-source software; (7) taking informed consent in low-resource settings is challenging; (8) big data offer promise, but social norms and SIM change constrain use; (9) successful government engagements require significant capacity; (10) define governance structures and roadmaps up front.