> For a complete page index, fetch https://docs.synthflow.ai/llms.txt. For full documentation content, fetch https://docs.synthflow.ai/llms-full.txt.

# Make a call

POST https://api.synthflow.ai/v2/calls
Content-Type: application/json

Initiates a real-time phone call through the AI agent.

Reference: https://docs.synthflow.ai/api-reference/platform-api/calls/voice-call

## Authentication

- `Authorization` header (bearer token, required)

## Servers

- `https://api.synthflow.ai/v2` (Global, default)
- `https://api.us.synthflow.ai/v2` (United States)
- `https://api.eu.synthflow.ai/v2` (European Union)

## Request

### Body (application/json)

- `model_id` (string, required) — Agent ID. You can find it on the agent’s page in your dashboard.
- `phone` (string, required) — Call recipient's phone number.
- `name` (string, required) — Call recipient's name.
- `from_phone_number` (string, optional) — Optional outbound caller ID. Must match a phone number attached to the outbound agent.
- `custom_variables` (list of object, optional) — Key-value pairs of pre-call variables, called custom variables in the API, that you can dynamically inject into the prompt. [Learn more](/variables#pre-call-variables).
  - `key` (string, optional)
  - `value` (string, optional)
- `lead_email` (string, optional) — The customer's email that can be used to book an appointment.
- `lead_timezone` (string, optional) — The customer's time zone that can be used to book an appointment. For a list of all available time zones, see [Time zones](/time-zones).
- `prompt` (string, optional) — The prompt that the agent will use.
- `greeting` (string, optional) — The greeting the agent will use.

## Response

### 200

200

- `status` (string, optional)
- `response` (object, optional)
  - `answer` (string, optional)
  - `call_id` (string, optional)
- `eta` (integer, optional) — How long it will take to initialize the call, in seconds.

## Examples

**Request**

```json
{
  "model_id": "1696372226173x164740052408336400",
  "phone": "+12345678987",
  "name": "David",
  "from_phone_number": "+16286666348",
  "custom_variables": [
    {
      "key": "Company",
      "value": "Synthflow"
    },
    {
      "key": "Role",
      "value": "Sales Specialist"
    }
  ],
  "prompt": "You are a helpful sales assistant.",
  "greeting": "Hello, this is Sarah calling from Acme Corp."
}
```

**Response**

```json
{
  "status": "success",
  "response": {
    "answer": "ok",
    "call_id": "1691579123700x31589864853004400"
  }
}
```

**SDK Code**

```python
import requests

url = "https://api.synthflow.ai/v2/calls"

payload = {
    "model_id": "1696372226173x164740052408336400",
    "phone": "+12345678987",
    "name": "David",
    "from_phone_number": "+16286666348",
    "custom_variables": [
        {
            "key": "Company",
            "value": "Synthflow"
        },
        {
            "key": "Role",
            "value": "Sales Specialist"
        }
    ],
    "prompt": "You are a helpful sales assistant.",
    "greeting": "Hello, this is Sarah calling from Acme Corp."
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.json())
```

```go
package main

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

func main() {

	url := "https://api.synthflow.ai/v2/calls"

	payload := strings.NewReader("{\n  \"model_id\": \"1696372226173x164740052408336400\",\n  \"phone\": \"+12345678987\",\n  \"name\": \"David\",\n  \"from_phone_number\": \"+16286666348\",\n  \"custom_variables\": [\n    {\n      \"key\": \"Company\",\n      \"value\": \"Synthflow\"\n    },\n    {\n      \"key\": \"Role\",\n      \"value\": \"Sales Specialist\"\n    }\n  ],\n  \"prompt\": \"You are a helpful sales assistant.\",\n  \"greeting\": \"Hello, this is Sarah calling from Acme Corp.\"\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.synthflow.ai/v2/calls")

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  \"model_id\": \"1696372226173x164740052408336400\",\n  \"phone\": \"+12345678987\",\n  \"name\": \"David\",\n  \"from_phone_number\": \"+16286666348\",\n  \"custom_variables\": [\n    {\n      \"key\": \"Company\",\n      \"value\": \"Synthflow\"\n    },\n    {\n      \"key\": \"Role\",\n      \"value\": \"Sales Specialist\"\n    }\n  ],\n  \"prompt\": \"You are a helpful sales assistant.\",\n  \"greeting\": \"Hello, this is Sarah calling from Acme Corp.\"\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.synthflow.ai/v2/calls")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"model_id\": \"1696372226173x164740052408336400\",\n  \"phone\": \"+12345678987\",\n  \"name\": \"David\",\n  \"from_phone_number\": \"+16286666348\",\n  \"custom_variables\": [\n    {\n      \"key\": \"Company\",\n      \"value\": \"Synthflow\"\n    },\n    {\n      \"key\": \"Role\",\n      \"value\": \"Sales Specialist\"\n    }\n  ],\n  \"prompt\": \"You are a helpful sales assistant.\",\n  \"greeting\": \"Hello, this is Sarah calling from Acme Corp.\"\n}")
  .asString();
```

```csharp
using RestSharp;

var client = new RestClient("https://api.synthflow.ai/v2/calls");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <token>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"model_id\": \"1696372226173x164740052408336400\",\n  \"phone\": \"+12345678987\",\n  \"name\": \"David\",\n  \"from_phone_number\": \"+16286666348\",\n  \"custom_variables\": [\n    {\n      \"key\": \"Company\",\n      \"value\": \"Synthflow\"\n    },\n    {\n      \"key\": \"Role\",\n      \"value\": \"Sales Specialist\"\n    }\n  ],\n  \"prompt\": \"You are a helpful sales assistant.\",\n  \"greeting\": \"Hello, this is Sarah calling from Acme Corp.\"\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "Authorization": "Bearer <token>",
  "Content-Type": "application/json"
]
let parameters = [
  "model_id": "1696372226173x164740052408336400",
  "phone": "+12345678987",
  "name": "David",
  "from_phone_number": "+16286666348",
  "custom_variables": [
    [
      "key": "Company",
      "value": "Synthflow"
    ],
    [
      "key": "Role",
      "value": "Sales Specialist"
    ]
  ],
  "prompt": "You are a helpful sales assistant.",
  "greeting": "Hello, this is Sarah calling from Acme Corp."
] as [String : Any]

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

let request = NSMutableURLRequest(url: NSURL(string: "https://api.synthflow.ai/v2/calls")! 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()
```