> 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 outbound SIP trunk

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

Creates an outbound trunk: the resource calls are placed through. Requires an
admin-role key. `numbers` are the caller IDs the trunk may present; a call or
campaign chooses among them per call via `fromNumber` / `fromNumbers`.

One trunk per carrier address per organization (`409` naming the existing trunk),
and a caller ID can live on only one of your outbound trunks (`409` naming it).
`address` and `transport` are immutable after creation: to change carriers, delete
the trunk and create a new one.


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

## 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)
- `address` (string, required) — Your carrier's SIP termination host: a hostname or IP, optionally with a port. Full `sip:`/`sips:` URIs are normalized to the bare host.
- `numbers` (list of string, required) — Caller IDs this trunk may present, E.164 with leading `+`.
- `transport` (enum, optional, default: auto)
  - Allowed values: `auto`, `udp`, `tcp`, `tls`
- `mediaEncryption` (enum, optional, default: disable)
  - Allowed values: `disable`, `allow`, `require`
- `destinationCountry` (string, optional) — ISO 3166-1 alpha-2 country code for region-pinned routing (optional).
- `cpsLimit` (integer, optional, default: 1) — Calls per second placed through this carrier address. Shared by every trunk on the same address in your organization.
- `authUsername` (string, optional)
- `authPassword` (string, optional)

## Response

### 201

Trunk created

- `status` (boolean, optional)
- `data` (object, optional)
  - `_id` (string, optional)
  - `livekitTrunkId` (string, optional)
  - `name` (string, optional)
  - `address` (string, optional) — The carrier termination host
  - `transport` (enum, optional)
    - Allowed values: `auto`, `udp`, `tcp`, `tls`
  - `numbers` (list of string, optional) — Caller IDs this trunk may present
  - `mediaEncryption` (enum, optional)
    - Allowed values: `disable`, `allow`, `require`
  - `cpsLimit` (integer, optional)
  - `authUsername` (string, optional)
  - `isActive` (boolean, optional)
  - `createdAt` (datetime, optional)
  - `updatedAt` (datetime, optional)

## Examples

**Request**

```json
{
  "name": "Acme carrier (outbound)",
  "address": "sip.acme.com:5060",
  "numbers": [
    "+14155552671"
  ]
}
```

**Response**

```json
{
  "status": true,
  "data": {
    "_id": "string",
    "livekitTrunkId": "string",
    "name": "string",
    "address": "string",
    "transport": "auto",
    "numbers": [
      "string"
    ],
    "mediaEncryption": "disable",
    "cpsLimit": 1,
    "authUsername": "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/outbound"

payload = {
    "name": "Acme carrier (outbound)",
    "address": "sip.acme.com:5060",
    "numbers": ["+14155552671"]
}
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/outbound';
const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: '{"name":"Acme carrier (outbound)","address":"sip.acme.com:5060","numbers":["+14155552671"]}'
};

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/outbound"

	payload := strings.NewReader("{\n  \"name\": \"Acme carrier (outbound)\",\n  \"address\": \"sip.acme.com:5060\",\n  \"numbers\": [\n    \"+14155552671\"\n  ]\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/outbound")

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 (outbound)\",\n  \"address\": \"sip.acme.com:5060\",\n  \"numbers\": [\n    \"+14155552671\"\n  ]\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/outbound")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"name\": \"Acme carrier (outbound)\",\n  \"address\": \"sip.acme.com:5060\",\n  \"numbers\": [\n    \"+14155552671\"\n  ]\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/outbound', [
  'body' => '{
  "name": "Acme carrier (outbound)",
  "address": "sip.acme.com:5060",
  "numbers": [
    "+14155552671"
  ]
}',
  '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/outbound");
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 (outbound)\",\n  \"address\": \"sip.acme.com:5060\",\n  \"numbers\": [\n    \"+14155552671\"\n  ]\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 (outbound)",
  "address": "sip.acme.com:5060",
  "numbers": ["+14155552671"]
] as [String : Any]

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

let request = NSMutableURLRequest(url: NSURL(string: "https://api.smallest.ai/atoms/v1/sip-trunk/outbound")! 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()
```