This document discusses a study that investigated the impacts of interactivity perceptions on English as a Foreign Language (EFL) learners' achievements in an Online Mobile Language Learning (OMLL) course. 68 Iranian intermediate EFL learners participated, with 43 participating in an OMLL course using mobile phones and 25 participating in conventional classrooms. The results showed that OMLL had significant positive effects on learners' achievements, but there are also challenges to conducting OMLL courses in the Iranian EFL context.