Cabrera González, Yunior Vicente, Danelis Garrido Guillán, and Elizabeth Guillán Joa. “PROPOSAL FOR THE DESIGN OF A PABX USING FREE HARDWARE AND SOFTWARE”. Telemática 19, no. 1 (May 11, 2020): 1–10. Accessed September 26, 2021. https://revistatelematica.cujae.edu.cu/index.php/tele/article/view/356.