IP whitelisting is a way to control who has access to information on your network. One way to ensure Sinch has authorized access is to add Sinch’s IP address(es) to WeChat IP whitelist in the Developer section of the WeChat Official Account admin portal. We recommend that you add to the IP whitelist when setting up WeChat channel in your Conversation API app. This is required by WeChat to ensure the request will be called successfully. See How do I configure a WeChat channel on the Conversation API? for more information.
The Sinch Developer Documentation site contains comprehensive documentation and tutorials, which show you how we support WeChat through the Sinch Conversation API.