Calling AI Model APIs from Mainland China: Latency, Reachability, and Choices
cdnping · 2026-10-17
"Can I use this API in China, and is it fast?" is the question developers ask most. The answer depends on three things: whether the network can reach it, whether the provider serves your region, and the fixed overhead of each request.
Reachability: Network Layer
Direct connection success rates to overseas model APIs (OpenAI, Anthropic, Google, xAI, etc.) fluctuate widely in mainland China and vary by carrier. Domestic providers (DeepSeek, Kimi, Zhipu, Alibaba Cloud Model Studio, Volcengine Ark, SiliconFlow) host their endpoints inside China, so direct connections are stable. cdnping'sStatus pageVisitors' measured success rates, grouped by China Telecom, China Unicom, and China Mobile.
Service regions: compliance
A working connection doesn't mean you can use the service. OpenAI and Anthropic both publish lists of supported countries and regions, and mainland China and Hong Kong are not on them; both refuse service based on where requests come from. Before choosing an overseas model, make sure your usage complies with its terms of service and your local laws.
Where latency comes from
- Connection setup: DNS resolution plus the TCP and TLS handshakes. Across oceans, each round trip takes 150–250 ms, and a new connection needs two or three round trips. SDKs reuse connections by default, so this only happens on the first request.
- Gateway round trip: The per-request overhead once a connection is reused, which is exactly what the "Round trip" column on the cdnping home page measures.
- Time to first token: Model queuing and inference, unrelated to the network and usually the largest part of total time. Streaming output noticeably improves perceived speed.
Recommendations
- First, checkStatus page30-day reachability and official incidents, to rule out unstable endpoints.
- on your real network using cdnping Speed test, and look at the two numbers: first connection and round trip.
- For latency-sensitive use cases (completions, real-time chat), prefer models hosted in China or gateways deployed close to your users.
Reading is good; testing it yourself is better.
Keep reading
- Native IP vs. Broadcast IP: Differences, How to Tell, and Common Misconceptions
- DNS leaks and WebRTC leaks: how they work, how to check, and how to fix them
- What Is Split Routing: Why Different Websites See You in Different Countries
- Choosing a Public Frontend CDN for Projects in China: jsDelivr, unpkg, cdnjs, and Domestic Mirrors