The aim of this experimental study was to find out the potential of using mobile phones in teaching English as a foreign language (EFL), specifically the use of Short Message Service (SMS) as a support tool in the EFL class. The research questions formulated for this project are the following: (1) Is using SMS messages via a mobile phone an effective tool in terms of motivation and engagement?; (2) What type of mini-lessons do subjects think are better to be sent via SMS in terms of effectiveness, engagement, and usefulness for their learning purposes?; (3) What is the appropriate timing for the activities to be sent?; and (4) Did students who participated in the project perform better than the control group? This experimental study lasted two academic years. As this was a preliminary study of the viability of the SMS methodology, it was conducted with a small group of students (n = 13) from the English Degree at the University Rovira i Virgili (Tarragona, Spain). Researchers designed various types of activities the first year, and used them though a period of 15 weeks. The aim of the first year was to answer research questions 1 through 3. The second year, a new set of exercises was created, with the aim of gathering data to be able to answer the fourth research question. Both qualitative data (from the first year) and quantitative data (from the second year) were analysed. Findings show that the subjects found the experience engaging. The subjects preferred receiving short and direct exercises which could be answered immediately. They preferred receiving the SMS in the afternoon or evening, and the results show that this methodology enhances the retrieval of memorized English language rules.