According to Wikipedia, a monopoly "exists when a specific individual or enterprise has sufficient control over a particular product or service to determine sig

According to Wikipedia, a monopoly "exists when a specific individual or enterprise has sufficient control over a particular product or service to determine significantly the terms on which other individuals shall have access to it.". Given Skype's market share (not Voip in general, but free worldwide voip calls), I would say they do have a monopoly.