I'm guessing that Africa is where we'll see the most exciting breakthroughs in mHealth. Need some evidence? Take a look at the latest Pew data on cell phone adoption.
Landline use is almost non-existent (and importantly, were really never used):
Cell phone use is surging.
Importantly, people are using their phones for texting. This is critical. We have dozens of evidence-based texting interventions for a wide range of conditions.
And we'll see rapid penetration, because people smartphone penetration is lagging. This may seem disadvantageous, but we've shown that you can deliver highly personalized, fully automated, health system linked interventions through regular old feature phones (who came up with that name). This means that there are no pesky [expensive, time intensive, expertise-demanding] visual interface issues to get in the way.
It's hard to overestimate how important these changes could be. When have we seen such rapid changes in infrastructure that can revolutionize the health system in low income countries?