Nusram, M., and C. E. Suharyanto. “IMPLEMENTASI VOIP SERVER BERBASIS LINUX ASTERISKNOW”. Computer and Science Industrial Engineering (COMASIE), vol. 3, no. 1, July 2020, pp. 63-73, https://forum.upbatam.ac.id/index.php/comasiejournal/article/view/2014.