If you want to host a VC with more than two locations involved you need to have a bridge.
I had to do a similar project last year and found www.polycom.com to be the best option. The ViewStationMP is probably the best for three way+ conferences.BT will host calls if each site has it's own kit and act as a bridge.They do this for ?40 per site, call charges are 18p per minute per site +standard call charges.
Here are a few questions you may want to ask of your company do we want to.
1 -Purchase a bridge outright
Purchasing a bridge outright MCI.com
Very expensive in the region of 20K+
2- Leasing VC equipment
?250 per day call charges fees etc still aply
http://www.vcs-ltd.com
3-Renew current VC equipment // I assume you don't currently have VC equipment
4-Using a bridgin host // This is the BT option
The option we went for was to have VC equipmet with it's own bridge from Polycom.com formely PitrueTel. The equipment cost around 7K.
The ViewStationMP is probably the best for three way+ conferences.
If however it is only for two way conferences then Netmeeting is as good as anything in the market and cheap.