This study aims to explore the use of the mobile-based English speaking application, Speaking English Jr. by Korean middle school teachers and students. A total of 510 students and 17 teachers from 15 middle schools in both rural and urban areas participated in this study. Data from two student surveys and student logs from the Learning Management System (LMS) were collected and quantitatively analyzed by using descriptive statistics and ANOVAs. The results indicate that although students in both areas like mobile phones (68.2%) and are proficient in using their functions (64.3%), few used their phones for education (6.8%). Most of their phone time was spent in messaging (62.1%), interacting with SNS (59.6%) and playing games (46.6%). In particular, 62% of the students in rural areas responded that they did not receive any educational assistant in studying English after school. However, after using the English speaking application program, the confidence level of these students in learning English significantly increased. The implications of the study suggest bridging the English achievement gap between students in rural and urban areas with assistance from the free educational application programs that have been developed based on the national curriculum for Korean students.