We are looking into offering the webinars over voice over IP in the future, our current provider of webinar software (webex) does not provide it in the particular version we use. Having said that calling to the USA is very cheap nowadays, not only with Skype as Marcel indicates (with Skype it is actually free if you use the 0800 number i think) but also with French telecom providers. For example if I go to Tele2’s website in France it tells me that it costs 0.06 cent per minute to dial USA. That means that attending a webinar would cost less then 4 euro.