---
title: "POST /billing/threeds/{id}/callback"
method: POST
path: "/billing/threeds/{id}/callback"
tags: ["Billing"]
---

# POST /billing/threeds/{id}/callback

`POST /billing/threeds/{id}/callback`

Provider-extensible Challenge callback. Its form fields are intentionally opaque and are verified by the gateway continuation instead of a field whitelist.

## Path parameters

- `id` string, uuid, required

## Response `200`

The payment completed or another browser action is rendered.

## Other responses

- `400` — The checkout identifier is invalid.
- `409` — Another signup completed this Product account.
- `413` — The callback exceeds the transport size limit.
- `422` — The gateway continuation could not be completed.
- `503` — The checkout continuation is temporarily unavailable.

---

[API](https://skmtc.dev/expertschat/apis/billing-core-api.md) · [All operations](https://skmtc.dev/expertschat/apis/billing-core-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/expertschat/billing-core-api/revisions/c6d0e986ce32/schema)