University students face the challenge of communicating in a foreign language while speaking. This is perceived as one of the most complex skills to develop. The lack of opportunities to interact in the target language, in and out of the English classrooms, prevents students from acquiring fluency and confidence. This study examines the development of students' oral communication skills of Level B1 (Pre-Intermediate level of the Common European Framework of Reference for Languages) of English as a Foreign Language (EFL) using the WhatsApp applications. Forty–five EFL learners aged 18-25 from a language center at a university in Ecuador performed exercises using voice messages and short videos as part of their course planned activities. The data collection method consisted of surveys and interviews with the participants and their teacher’s observations. Data were analyzed using descriptive statistics and cross-tabulation accordingly. Analysis of the data evidenced that short videos were far more effective than voice messaging in improving the participants' oral communication skills. Other benefits were the improvement of grammar and pronunciation observed in the learners' voice messages, with the consequent improvement of their speaking fluency. It can be said that the participants' overall oral communication skills developed with the use of the WhatsApp application in this study. Therefore, the authors recommend exploring the application of technological resources in the EFL classroom.