I think the reason China is excluded is probably because China gets its own customised Skype as opposed to using the standard client. https://support.skype.com

I think the reason China is excluded is probably because China gets its own customised Skype as opposed to using the standard client. https://support.skype.com/en/faq/FA10910/what-is-tom-online https://support.skype.com/en/faq/FA10910/what-is-tom-online