> For the complete documentation index, see [llms.txt](https://wallee.gitbook.io/documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wallee.gitbook.io/documentation/payments/in-store-payments/integrations/interfaces/local-interface.md).

# Local Interface

**Local Till Interface:** By using the local till interface you connect directly with a socket to the terminal device. The benefit is that you have a fast connection as both your application and the terminal device are in the same local network. The drawback is that you need to know the terminal's IP address. The [Local Till Interface documentation](https://lti.docs.wallee.com/) changes depending on the application version installed on the terminal device.

### 1. Prerequisites

* A registered terminal (TID assigned, PayDroid OS and {inject-brand-name} App up to date).
* Local Till API feature enabled in the terminal configuration.
* POS device must be on the **same local network** as the terminal.
* Ensure firewall allows LAN traffic between POS and terminal.

***

### 2. Discovering the Terminal

There are two common ways to connect:

1. **mDNS / Bonjour discovery** – POS automatically finds available terminals on the LAN.
2. **Static IP assignment** – Terminal is configured with a fixed IP address, and the POS connects directly.

Example discovery response:

```json
{
  "terminalId": "32518857",
  "ip": "192.168.1.45",
  "port": 8080
}
```

***

### 3. Starting a Transaction

Once the terminal is reachable, send a **POST request** to its local API:

```http
POST http://192.168.1.45:8080/transactions/start
Content-Type: application/json
```

Example request body:

```json
{
  "amount": {
    "currency": "CHF",
    "value": "23.60"
  },
  "transactionType": "PURCHASE",
  "reference": "ORDER-12345"
}
```

Response:

```json
{
  "transactionId": "abc123",
  "status": "PENDING"
}
```

***

### 4. Receiving Status Updates

The terminal can notify the POS of status changes via **WebSocket callback** or by polling the API.

Example status event:

```json
{
  "transactionId": "abc123",
  "status": "APPROVED",
  "amount": {
    "currency": "CHF",
    "value": "23.60"
  },
  "reference": "ORDER-12345",
  "timestamp": "2025-09-25T10:24:00Z"
}
```

***

### 5. Testing the Integration

1. Connect POS and terminal to the same LAN.
2. Trigger a small test transaction.
3. Verify the terminal prompts the customer.
4. Check that the POS receives the status update and final transaction result.