Sallam Bro zumrwai ..
well ur talking about Vidoe Conferencing Systems ... Voice Over Ip Network..surelything u need a special kind of gatewayz to do such a things...and this kind of networkin .. called data communication network...well about voicez gateways we haev so many kind og gatewayz can help u to run vidoe/voice over ip ..such as:
1-A powerful, flexible video network server. A four slot, hot swap chassis for Gateway, MCU and application solutions
2- Primary Rate E1/T1 or 4BRI
1U Gateway solution based on the ViaIP Technology
2- TANDBERG ISDN/IP Multipoint System for up to 16 sites Supporting data rates to 2Mb/s on ISDN and. Feature rich with Encryption and up to 16 way continuous presence.
3- VCB 2500 is VCON's solution for multipoint videoconferencing and streaming with other advanced features enabling the largest deployment flexibility in today's marke
i hope i help u out about data communicationz and stuff .. if u still confused .. keep asking and i'll try my best
regards
MOe