When using packet-switched Internet protocols, video and audio are dealt with separately. ISDN video and audio arriving at the MICE Conference Management and Multiplexing Centre (CMMC) at UCL are separated and combined with video and audio data sent from hardware or software codecs over the Internet. The video is presently combined and processed with other video in the analogue domain, and further processed so all conferees can see the ISDN video, and the ISDN caller can see the MICE video (usually a quad image showing video from 4 sites). The audio is combined with other audio inputs using VAT (Visual Audio Tool, a multicast audio tool from Lawrence Berkeley Laboratory) to enable all conferees to hear the ISDN caller, and enable the ISDN caller can join in the audio conference.
To date, both a Tandberg videophone and BT codecs with a terminal adaptor have been successfully used for demonstrating interworking with ISDN between UCL and sites in the UK and with MICE partners in Europe: mainly Norwegian Telecom Research (NTR) but also sites in Germany and France.
Due to lack of suitable hardware for Primary Rate connections, current demonstrations have been limited to interworking with Basic Rate service has been used, using either 1 or 2 B channels.