In my opinion, one of the major challenges people face in developing economies is lack of information. By using communication devices such as cellphones, ID organizations are able to deliver critical information to individuals, whether it's commodity prices to farmers or vaccine availability to health clinics.
One of the communication platforms that is highly used in the developing world is
RapidSMS, which is a free open-source framework that utilizes text messaging to "manage data-collection,
complex workflows, and group coordination using basic mobile phones". UNICEF is large supporter of this framework and has customized it to meet the needs of the various countries they operate in such as Malawi, Ethiopia, and Rwanda.
In Rwanda, it all started with the government awareness of the critical health problem the country faces in the area of maternity and child mortality. Rates were growing not only because of lack of medical care but also because of lack of education, awareness, and timely treatment. President Kagame distributed 60,000 cellphones to Community Health Workers (CHW) which are volunteers from the community responsible for the front-line care of a number of patients in their area, 15,000 of these cellphones were solely designated for maternal and child health. UNICEF took this opportunity to employ RapidSMS in aiding the CHWs and patients.
Here is how it works: CHWs would register women in their village as they become pregnant. These women are then tracked and monitored during check ups by using a variety of codes (see example below). In the case of emergencies, medical professionals and ambulance would be notified. All the information submitted by CHWs is stored in a central database that aggregates reports for the Ministry of Health to create nation-wide monitoring of diseases and epidemics.

Since it's roll-out in 2009, this technology has had great impact in reducing maternal deaths. One of the doctors we met with in Rwanda said that his hospitals has experienced zero maternal deaths in the year they implemented RapidSMS, compared to 10 in the previous year. However, there are still challenges that prevent this technology from being very effective. One of those is lack of electricity, CHWs are struggling to charge their cellphones. Some have to walk 2 hours on average to a charging station, these stations are very chaotic (photo below) and phones are often lost or stolen. One solution would be for the government to partner with local renewable energy providers such as
Great Lakes Energy which produces portable solar panel phone chargers to supply CHWs. I believe this will lead to both sustainable and effective work in rural areas where electricity is scare and disease is high.
A photo of a cellphone charging station