Higher levels of device ownership and lower connectivity requirements are key reasons why mobile learning may have potential to support education at scale in low-income contexts. Interest in the use of mobile phones as an educational medium - particularly through the use of SMS or messaging apps - has been renewed recently, as a result of school closures prompted by the Covid-19 pandemic. As a result, the evidence base for educational interventions using SMS at scale has recently expanded. In this work-in-progress synthesis paper, we review recent research studies which have used SMS for education at scale, with findings published since the onset of the Covid-19 pandemic in 2020. We find that there has been a notable increase in studies which have used SMS to promote and support education at a large scale. In addition to its use as a medium for directly supporting learners, it has also been applied to promoting parental engagement and encouraging participation in formal schooling. The efficacy of interventions has been mixed, which highlights the need for nuance and further research as the field looks to understand which benefits of mobile learning could be beneficial to retain post-pandemic.