The 21st century education advocates providing students with multi-modal learning experiences alongside creating a path to autonomous learning. In this regard, mobile learning, or the M-learning is gaining popularity in the field of education. Today, its use in the area of teaching and learning is actively and widely explored especially in the higher education to encourage learning across contexts, subjects, and time through social and content interaction. The use of mobile apps in English language teaching is largely looking at how it impacts on students’ writing and speaking skills. Limited attention has been given to how the apps, particularly their asynchronous medium can support students’ collaborative learning. This paper examines the communication strategies used by postgraduate students, who are also in-service teachers, using the asynchronous WeChat mobile app for academic problem-solving purposes. It also explores their opinions on the practicality of using the oral asynchronous communication programme for problem-solving activities. This attempt is accomplished by employing a mixed-method approach where a quantitative frequency count of communication strategies used in the WeChat problem-solving activities is cross-referenced with retrospective interviews. The findings shed light on teaching and learning via oral-based asynchronous medium pertaining to the types of tasks and learning objectives to be achieved.