bsnl broadband video conferencing?

Hi friends
i got a problem here in Nagercoil in Broadband Video conferencing using Static IP address mode.
The problem is the subscriber is able to video conference through Airtel network to london but the same subscriber is not able to do the same through BSNL Broadband.Already enquired in NIB Bangalore for assistance if any ort is closed open the port so that the problem will be solved but the reply from bangalore is that all ports are open no problem in NIB.So wat may be the reason for the above?
Local video conferencing is possible through BSNL Broadband but internationaly not why?any answers ?