Push-to-Talk (PTT) is a one-way voice group communication. It is very simple and easy to operate the PTT conversation. A talker presses the “talk” button of a PTT session to speak and the other group members in the same PTT session will simultaneously hear the talk at one time. The PTT has also been widely used in practical military, police, security, rescue, and emergency radio communications for many years. PTT service is also annunciated in mobile telecommunication, it is called Push-to-Talk over Cellular (PoC). Context-awareness is a mechanism to present the state information of users, devices, or environments according to their situations. Thus, a user can obtain a reasonable and proper service among these context-aware interactions. It is also extensively used in personal mobile communication for designing a ubiquitous communicating environment in many researches. In this paper we will combine the features of PTT and context-aware service to design a context-aware Push-to-Talk service. The PTT service can be aware to filter context information and to form an applicable PTT session according to the current contexts of PTT users.