Khemakongkanonth, Chate, and Chokchai Netngamsawang. “The Competition in Voice Service Market between Network Operators and OTT Service Providers”. Journal of Digital Communications 7, no. 1 (June 19, 2023): 109–127. accessed September 22, 2026. https://so04.tci-thaijo.org/index.php/NBTC_Journal/article/view/260756.