---
title: "Create an SMS topic"
description: "Create an SMS subscription topic. `POST /api/v1/sms/topics`"
url: https://www.unitpost.com/docs/sms/post-sms-topics
section: "SMS API reference"
updated: 2026-10-13
---
# Create an SMS topic

`POST /api/v1/sms/topics`

Create an SMS subscription topic. `default_opt_in` decides whether contacts with no explicit preference are treated as subscribed. Names are unique per channel, so an SMS topic may share a name with an email topic. Topics are a plan feature: an unentitled workspace gets `403` with `limit_reached`. Requires the `topics:write` capability.

## Request body

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `name` | string | yes | — |
| `description` | string | no | — |
| `default_opt_in` | boolean | no | — |

## Response fields (201)

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `object` | string | yes | — |
| `id` | string | yes | — |
| `name` | string | yes | — |
| `description` | string \| null | yes | — |
| `channel` | enum | yes | Which channel the topic belongs to. Email topics are managed under `/email/topics`, SMS topics under `/sms/topics`. One of: `email`, `sms`. |
| `default_opt_in` | boolean | yes | — |
| `created_at` | string | yes | — |
| `updated_at` | string | yes | — |

## Responses

| Status | Description |
| --- | --- |
| 201 | Created. |
| 401 | Missing or invalid API key. |
| 403 | Insufficient scope, or topics aren't on your plan (`limit_reached`). |
| 404 | SMS is not enabled for this workspace. |
| 409 | An SMS topic with that name already exists. |
| 422 | Validation error. |

## Example request

```bash
curl -X POST 'https://www.unitpost.com/api/v1/sms/topics' \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -d '{ }'
```

## Example response (201)

```json
{
  "object": "topic",
  "id": "id_123",
  "name": "Example",
  "description": "string",
  "channel": "email",
  "default_opt_in": false,
  "created_at": "2026-01-01T00:00:00.000Z",
  "updated_at": "2026-01-01T00:00:00.000Z"
}
```

## Links

- HTML reference (with Node.js, Python, Ruby, PHP, Go, Java, Rust, .NET and CLI examples): https://www.unitpost.com/docs/sms/post-sms-topics
- OpenAPI 3.1 (full schemas): https://www.unitpost.com/api/v1/openapi.json