estimating VoIP data traffic size from VoIP signaling traffic size ?

Hi, is there any statistics on aggregated VoIP signaling bandwidth and aggregated VoIP data bandwidth? eg. if we monitored there is 2Mbps(average) traffic on VoIP signaling protocol ports ( including SIP, H.323, MGCP), how could we estimate average VoIP data bandwidth? Joe __________________________________ Meet your soulmate! Yahoo! Asia presents Meetic - where millions of singles gather http://asia.yahoo.com/meetic