> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Create an inbound SIP trunk

POST https://api.smallest.ai/atoms/v1/sip-trunk/inbound
Content-Type: application/json

Creates an inbound trunk: the resource that receives calls from your carrier.
Requires an admin-role key. An inbound trunk needs at least one phone number
or one allowed peer address; the trunk gets its own credentials,
media-encryption policy, Krisp toggle, and ringing timeout.

Phone numbers are unique across the platform: a number already answering
elsewhere returns `409` ("Already in use and cannot be added to this trunk: ...").
Wildcard peer addresses (`0.0.0.0`, `::`, `*`, any `/0`) are refused, since the
allow-list is the security boundary.


Reference: https://docs.smallest.ai/voice-agents/api-reference/sip-trunks/create-inbound

## Authentication

- `Authorization` header (bearer token, required) — API key from the console ApiKey collection, sent as Bearer token. Also accepts session cookies for browser-based auth.

## Request

### Body (application/json)

- `name` (string, required) — Display name for the trunk
- `numbers` (list of string, optional) — E.164 numbers (with leading `+`) this trunk answers. Deduplicated.
- `allowedAddresses` (list of string, optional) — Hostnames, IPs, or CIDR ranges allowed to send calls to this trunk. Wildcards refused.
- `allowedNumbers` (list of string, optional) — Restrict accepted caller numbers to this list (optional). If set, the trunk is dedicated even without `numbers`.
- `mediaEncryption` (enum, optional) — Defaults to `allow`.
  - Allowed values: `disable`, `allow`, `require`
- `krispEnabled` (boolean, optional) — Noise cancellation for callers arriving on this trunk. Defaults to `true`.
- `ringingTimeoutSeconds` (integer, optional)
- `authUsername` (string, optional) — SIP digest username. Provide both credentials or neither.
- `authPassword` (string, optional) — SIP digest password. Stored with the SIP infrastructure, never returned.

## Response

### 201

Trunk created

- `status` (boolean, optional)
- `data` (object, optional)
  - `_id` (string, optional)
  - `livekitTrunkId` (string, optional)
  - `name` (string, optional)
  - `numbers` (list of string, optional) — E.164 numbers this trunk answers
  - `allowedAddresses` (list of string, optional)
  - `allowedNumbers` (list of string, optional)
  - `mediaEncryption` (enum, optional)
    - Allowed values: `disable`, `allow`, `require`
  - `krispEnabled` (boolean, optional)
  - `ringingTimeoutSeconds` (integer, optional)
  - `authUsername` (string, optional) — Digest username, when set. The password is never returned.
  - `sipHost` (string, optional) — The SIP origination host to point your carrier at. Derived at read time (not stored) and identical for every trunk in the environment. Append a transport when configuring your carrier: `;transport=tls` (preferred) or `;transport=tcp`. The dashboard shows the same value in each inbound trunk's **Connection details** dialog. Returned on list and create responses; update responses omit it.
  - `agent` (object, optional, nullable) — The agent that answers on this trunk, or null
    - `id` (string, optional)
    - `name` (string, optional)
  - `isActive` (boolean, optional)
  - `createdAt` (datetime, optional)
  - `updatedAt` (datetime, optional)

## Examples

**Request**

```json
{
  "name": "Acme carrier (inbound)"
}
```

**Response**

```json
{
  "status": true,
  "data": {
    "_id": "string",
    "livekitTrunkId": "string",
    "name": "string",
    "numbers": [
      "string"
    ],
    "allowedAddresses": [
      "string"
    ],
    "allowedNumbers": [
      "string"
    ],
    "mediaEncryption": "disable",
    "krispEnabled": true,
    "ringingTimeoutSeconds": 1,
    "authUsername": "string",
    "sipHost": "5rdbhjuwtlk.sip.livekit.cloud",
    "agent": {
      "id": "string",
      "name": "string"
    },
    "isActive": true,
    "createdAt": "2024-01-15T09:30:00Z",
    "updatedAt": "2024-01-15T09:30:00Z"
  }
}
```

**SDK Code**

```python
import requests

url = "https://api.smallest.ai/atoms/v1/sip-trunk/inbound"

payload = { "name": "Acme carrier (inbound)" }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.json())
```

```javascript
const url = 'https://api.smallest.ai/atoms/v1/sip-trunk/inbound';
const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: '{"name":"Acme carrier (inbound)"}'
};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go
package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.smallest.ai/atoms/v1/sip-trunk/inbound"

	payload := strings.NewReader("{\n  \"name\": \"Acme carrier (inbound)\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby
require 'uri'
require 'net/http'

url = URI("https://api.smallest.ai/atoms/v1/sip-trunk/inbound")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"name\": \"Acme carrier (inbound)\"\n}"

response = http.request(request)
puts response.read_body
```

```java
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://api.smallest.ai/atoms/v1/sip-trunk/inbound")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"name\": \"Acme carrier (inbound)\"\n}")
  .asString();
```

```php
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.smallest.ai/atoms/v1/sip-trunk/inbound', [
  'body' => '{
  "name": "Acme carrier (inbound)"
}',
  'headers' => [
    'Authorization' => 'Bearer <token>',
    'Content-Type' => 'application/json',
  ],
]);

echo $response->getBody();
```

```csharp
using RestSharp;

var client = new RestClient("https://api.smallest.ai/atoms/v1/sip-trunk/inbound");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <token>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"name\": \"Acme carrier (inbound)\"\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "Authorization": "Bearer <token>",
  "Content-Type": "application/json"
]
let parameters = ["name": "Acme carrier (inbound)"] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://api.smallest.ai/atoms/v1/sip-trunk/inbound")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```