Multilingual classrooms in developing countries are often challenged by a lack of digital resources and technology which supports their multilingual learning process. "Code-switching" is a phenomenon common to multilingual schools where learners are taught in a language which is not their first language. In these environments, code-switchers frequently alternate between their first and second languages, seeking alternative words to clarify their understanding of the topic being studied. This paper presents a study based in South Africa, where mathematics learners interacted with a mobile learning system named M-Thuto, supporting learners who code-switch while learning and providing them with digital resources. The system consisted of summarised notes, class exercises and a class quiz. Through semi-structured interviews and questionnaires, data were gathered and analysed from 90 learners to gain perspectives on their interaction processes. The study aimed to establish how mobile learning can be used to support multilingual learners in under-resourced schools. The results of the study reflect the need for mobile learning resources that support their learning considering their linguistic challenges. The results also reflect the important role that mobile phones can play as alternative digital learning resources.