The 21st century education is to provide students with digital learning experiences alongside creating a path to independent and collaborative learning. In this regard, computer-mediated communication (CMC) is receiving great attention in the field of education. Using a case study mixed methods approach, 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. It is found that the asynchronous spoken medium triggers 'presentation speech' patterns that reflect both spoken and written features. The problem-solving process in the asynchronous spoken medium also is mediated via a low frequency of the use of communication strategies. 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.