Relay

Receives text messages sent to a Danish virtual mobile number and e-mails sent to its e-mail domain, sends text messages, and makes it all available to your services and AI assistants.

+45 5454 2424

Every SMS sent to this number is stored here, and you can send SMS through the gateway. Use it in two ways:

• REST API for scripts, backends and integrations.
• MCP server so Claude, ChatGPT and other AI clients can look up messages for you, for example to read a one-time code.

Both require an access key. Reading and sending use separate keys. Ask the owner of this service for one.

REST API

GET https://relay.dtres.dk/api/sms returns the latest received messages as JSON, newest first.

Authentication

Send your key in one of these headers:

Authorization: Bearer <your-key>
X-Api-Key: <your-key>

A missing or wrong key returns 401 Unauthorized.

Query parameters

Example

curl -H "Authorization: Bearer <your-key>" \
  "https://relay.dtres.dk/api/sms?limit=20"

[
  {
    "id": "01a14507-5c1e-4c3a-9f0e-2b7d8a1e6f10",
    "from": "4550515946",
    "to": "4554542424",
    "text": "Your code is 123456",
    "receivedAt": "2026-10-16T14:04:57.03+00:00"
  }
]

Polling for new messages

Store the newest receivedAt from each response and pass it as since on the next call. You then only get messages you have not seen.

curl -H "X-Api-Key: <your-key>" \
  "https://relay.dtres.dk/api/sms?since=2026-10-16T14:04:57.03Z"

Send SMS

POST https://relay.dtres.dk/api/sms/send sends one SMS. It needs a send key (a read key is not enough), in the same headers as above.

curl -X POST "https://relay.dtres.dk/api/sms/send"   -H "Authorization: Bearer <your-send-key>"   -H "Content-Type: application/json"   -d '{"from":"54542424","to":"12345678","message":"Hello"}'

{
  "id": "019a0f3c-7b1e-7c3a-9f0e-2b7d8a1e6f10",
  "from": "4554542424",
  "to": "4512345678",
  "message": "Hello",
  "flash": false,
  "encoding": "gsm7",
  "status": "Sent",
  "smsCount": 1,
  "statusDescription": null,
  "errorCode": null,
  "createdAt": "2026-10-20T19:30:00+00:00",
  "sentAt": null,
  "doneAt": null
}

Delivery status

GET https://relay.dtres.dk/api/sms/outgoing lists sent messages, newest first (limit, since as above), and GET https://relay.dtres.dk/api/sms/outgoing/{id} returns one. A send key or a read key works. status is one of Pending, Sent, Delivered, Failed, Cancelled or Rejected, and is updated when the operator reports the final result.

MCP server

The Model Context Protocol server lets an AI assistant read the messages directly. Ask it things like "What was the last SMS I received?" or "Find the verification code from the latest message." It can also read one-time codes sent by e-mail.

Tools

All tools except send_sms are read-only. A normal MCP key cannot send; sending needs a separate MCP send key.

Claude (claude.ai and Claude Desktop)

1. Open Settings → Connectors and choose Add custom connector.
2. Name it, for example Relay, and enter the URL https://relay.dtres.dk/mcp.
3. Under advanced settings, choose no sign-in and add the request header Authorization with the value Bearer <your-key>.
4. Save, and enable the connector in a chat from the tools menu.

Custom request headers on connectors are not yet available on every Claude plan. If you do not see the option, use Claude Code below or the REST API.

Claude Code

claude mcp add --transport http sms https://relay.dtres.dk/mcp \
  --header "Authorization: Bearer <your-key>"

ChatGPT

In the ChatGPT desktop app and Codex, add an MCP server with these settings:

1. Type: Streamable HTTP.
2. URL: https://relay.dtres.dk/mcp.
3. Bearer token: set an environment variable on your computer, e.g. SMS_GATEWAY_KEY=<your-key>, and enter its name as the bearer token environment variable.

Or in ~/.codex/config.toml:

[mcp_servers.sms]
url = "https://relay.dtres.dk/mcp"
bearer_token_env_var = "SMS_GATEWAY_KEY"

ChatGPT on the web and in the mobile apps only supports MCP servers with OAuth sign-in, which this service does not offer yet.

Other MCP clients

Any client that supports Streamable HTTP and custom headers works. A generic JSON configuration:

{
  "mcpServers": {
    "sms": {
      "type": "http",
      "url": "https://relay.dtres.dk/mcp",
      "headers": { "Authorization": "Bearer <your-key>" }
    }
  }
}