CommCare works on two mobile systems- Android smartphones and J2ME/Java/Nokia-style feature phones. This article provides links to our best practices for procuring and managing such devices for both small- and large-scale projects.
Main page: CommCare for Feature Phones
SkillTrain in India-based social enterprise that develops training resources for vocational trainings like mobile phone or other electronics repair. They have videos available on their YouTube channel (in Hindi) that address some basic skills like transferring files between mobile phone and computer, and basic use of smartphones, in addition to advanced mobile repair techniques.