C.Gomathi, R.Anandhi, T.Aravindan,C.Elavarasan, R.Ramya. 2017. “TRANSFERRING VOICE OVER LOCAL AREA NETWORK THROUGH INTERNET PROTOCOL-PRIVATE BRANCH EXCHANGE”. International Journal of Engineering and Computer Science 2 (04). india. http://ijecs.in/index.php/ijecs/article/view/577.