Another suggestion that few people are utilizing yet is Skype. It is software for your computer that can be used for video conferencing but also regular phone calls. The calls are made over your computer, with no need of buying new hardware as needed with Vonage. The exact price would be dependent on your needs, but calls to China are $0.021/min.
Other benefits are the ability to perform conference calls, bring your phone number anyway, get voicemail online, etc. I think this is the way people will be going in the future, especially with the virtualization of technology.
For more info,
http://www.skype.com/prices/