Voip for a call in internet TV Variety show

we host an internet tv variety show where we have guests come on etc. What we would like to do is make the show interactive with both audio and video with our views all around the world.
At the moment local viewers are able to call us to a local number but we want to make it possible for international calls using voip. We tried it with skype and msn messenger but the feed back and delay was a big problem.
We have a dedicated server and an adobe 3.5 server installed.
I guess what we are trying to do is like Video Conferencing but instead of using phone lines we want to use the internet.

Any ideas on how this can be done?

Where are the majority of the people who are calling in to you located? Best idea is to set up a local number in those locations and use a VoIP device at your end or ask your local teleco to give you an international 'freephone' number for callers if you want to be charitable.

No sense in paying out big money for a hardware solution as inbound calls currently cost you nothing so I am having trouble seeing a financial advantage to using VoIP

Thanks for your reply Gary, but the idea is that the calls don't cost anybody anything. If you viewers have to pay for an international call they simply won't bother calling. The idea is to make our live programs 100% interactive audio and video.
Callers could be viewers located anywhere in the world. I am not very clear as to what you mean by a "VoIP device" and "international 'freephone' number". I am based in Panama and telecomunication services here are not what they are in the rest of the world.

Skype can give very clear sound and video but you do need a good internet connection with plenty of bandwidth. One problem that you may have is other services running on your network that may ruin the quality of the Skype call. It would probably best to have a separate internet connection dedicate to this service. It is not uncommon for broadcasters such as the BBC and CBC to use Skype audio and sometimes video when that is all that is available. There are also SIP based audio/video clients that can give similar quality to Skype but they also need good bandwidth.

If it is audio feed back that you are getting then that can be cured by using headphones or making sure that speakers/microphone are correctly configured. I can talk to a relative in the UK using a monitor Webcam/microphone without any feedback. Delay should not bet a problem so that is probably due to lack of adequate bandwidth.

I think the best idea is for me to show you and example of one of our shows...

http://www.walkaboutiptv.com/mediadetai ... rrasquilla

as you can see with this type of show head phones would look a little silly but yes we have tried skype and yes the problem was feedback.
The things is we are broad casting to two audiences 1. the live audience on the set and 2. the internet audience world wide. We are able to take calls locally within Panama using a Hybrid system that works well but we would really like to involve people from any where in the world via voip.
Dealy is another problem we have faced with anything we have tried so far.
Maybe my ideas are a little ahead of their time but I still believe there is a way this can be done successfully.

Anyway thanks very much for you help and if you think of anything please let me know.

Joe