Disclosure and availability: DaoXE is a multi-model, multi-protocol API gateway we operate (OpenAI Chat Completions, OpenAI Responses, Anthropic Messages / Claude protocol, and image-generation-compatible endpoints — not OpenAI-only, not Claude-only). It is not available in mainland China. This article is for developers in regions allowed by the service terms. The checklist works for any OpenAI-compatible gateway, not just DaoXE.
If you build software from Vietnam, Indonesia, Turkey, or a dozen other places, you know a failure mode that rarely shows up in English tutorials: the model works fine, but the billing page doesn't. An international card gets declined, a region isn't in the dropdown, or a subscription won't activate. The code is not the problem. The checkout is.
This post is the practical checklist I use when the goal is "get a real request through," separate from "argue with a payment form." It assumes you route through a gateway that already handles billing in a way you can actually complete, and it focuses on proving the integration is correct.
1. Separate the two failures
Write them down as two different problems:
