1. Internet phone: Changing the telephony paradigm?;Babbage;BT Technol. J.,1997
2. Convergence and new regulatory frameworks;Ono;Telecommun. Policy,1998
3. D. Clark, A Taxonomy of Internet Telephony Applications, http://www.itel.mit.edu:/itel/pubs/ddc.tprc97.pdf, 1997.
4. D. Krupinski, Introduction to Internet Telephony, http://www.phonezone.com/tutorial/it-intro.htm, 1997.
5. VocalTec Communications, Annual Report'98, 1998.