The purposes of this study were to 1) develop an English communication mobile application based on emergency medical service situations to meet efficiency criterion E1/E2 = 80/80; 2) compare the students' English communication skills before and after implementing the mobile application; and 3) examine the students' attitudes toward the use of the mobile application. The participants were 14 second-year students enrolled in an English for Specific Purposes course. The instruments were 1) a mobile application for English communication, 2) lesson plans, 3) Process E1 and Product E2 tests, 4) a role-play pretest and a posttest, and 5) an attitude questionnaire. The mobile application included videos featuring speakers with different English accents who used English as their lingua franca. Data were analyzed through Means, Standard Deviation, and the efficiency criterion of E1/E2. The findings revealed that the efficiency of the mobile application was 82.50/82.38 higher than the standard criteria (80/80). The students' English communication skills improved significantly following the use of the mobile application. The students held positive attitudes towards all aspects of the mobile application. The mobile application could prove valuable not only to paramedics but also to other medical professionals dealing with patients from different linguistic backgrounds.