---
title: "Upload opt-in form proof"
method: POST
path: "/v1/sms/opt-in-proof"
tags: ["SMS"]
---

# Upload opt-in form proof

`POST /v1/sms/opt-in-proof`

Hosts a screenshot (or PDF) of your SMS opt-in form and returns its
public URL. Include that URL in the campaign's `messageFlow` (the
opt-in workflow text) — the carrier registry has no attachment field,
so reviewers verify consent by opening links in that answer. Works
before a registration exists (use it when registering) and for
appeals. `/v1/sms/registrations/{id}/opt-in-proof` is an alias.

## Response `200`

File hosted.

- object
  - `url` string — Public URL to reference in the opt-in flow text.

## Other responses

- `401` — Unauthorized
- `422` — Unsupported file type or file too large

---

[API](https://skmtc.net/zernio/apis/zernio-api.md) · [All operations](https://skmtc.net/zernio/apis/zernio-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/zernio/zernio-api/revisions/3c7cf84cec44/schema)