HELP: VOIP Call China

Learned so much from everyone here, and bought a SPA1001 myself. Then registered at spigate.com and received a 724 area code number for my home phone, a handset phone. With this phone, I can receive calls and dial out to domestic numbers, within USA. Now I'm trying to call China, and searched for a few providers, such as VOIPZoom and VoipDiscount, etc. It all seemed to me that I have to use my computer to make a call. Did I read it right? How can I call China using my handset phone,(or cell phone), with my current VOIP settings?
Thanks all in advance.