This study investigates the effects of voice chat on Korean EFL learners` speaking ability according to their proficiency levels. With the purpose of the study, 181 college students in Korea were recruited to participate in an English speaking program that was designed to assist their speaking ability development. Participants were divided into three proficiency levels: beginning-level, intermediate-level, and advanced-level. They were then further divided into three voice chat conditions: voice chat with peers, voice chat with chatbots, and control. During the sixteen weeks of the experiment, the participants were asked to engage in one of the different types of voice chat. Before and after the actual experiment, they were required to take pre- and post-tests based on TOEIC Speaking Test by ETS. The study found positive improvements in speaking ability for the participants at all proficiency levels as a result of participating in voice chat. All the participants demonstrated statistically significant speaking ability improvement across the different chat conditions. Furthermore, all the participants at different proficiency levels showed more positive perceptions of English language learning after engaging in voice chat. It can be suggested that voice chat provides EFL learners with ample opportunities to practice speaking, reduces negative feelings and develops positive perceptions of English language learning, and consequently, improves their speaking skills.