, : -- -- SDN : 21 SDN 14, 2016 0 0 0 5 ISDN 1988 05, 2018 0 0 1 4 (NVF) 30, 2016 2000 0 0 5 VoIP 15, 2016 1000 0 0 4 SIP PSTN? 30, 2016 0 0 0 4 H.323 28, 2016 0 0 0 3 H.323 20, 2016 0 0 0 3 SIP PRI 08, 2016 3000 1000 0 5 BRI (basic rate interface) 25, 2015 0 0 0 3 VoIP ? 05, 2016 2000 0 0 6 1 2 3