Nixflex - AI Voice Platform for Building AI Phone Agents

Create batch campaign

curl --request POST \
  --url https://api.nixflex.com/v1/calls/batch

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.nixflex.com/v1/calls/batch",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://api.nixflex.com/v1/calls/batch"

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

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

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

	fmt.Println(string(body))

}

require 'uri'
require 'net/http'

url = URI("https://api.nixflex.com/v1/calls/batch")

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

request = Net::HTTP::Post.new(url)

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

POST

calls

batch

Create batch campaign

curl --request POST \
  --url https://api.nixflex.com/v1/calls/batch

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.nixflex.com/v1/calls/batch",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://api.nixflex.com/v1/calls/batch"

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

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

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

	fmt.Println(string(body))

}

require 'uri'
require 'net/http'

url = URI("https://api.nixflex.com/v1/calls/batch")

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

request = Net::HTTP::Post.new(url)

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

Creates a batch campaign: queues many outbound calls under one campaign ID. Useful for appointment reminders, lead qualification, surveys.

Request

curl -X POST https://api.nixflex.com/v1/calls/batch \
  -H "Authorization: Bearer KEY_ID:KEY_SECRET" \
  -H "Content-Type: application/json" \
  -d '{
    "agent_id": "agent_125207e452f8714a",
    "from_number": "+447446466847",
    "name": "Tuesday appointment reminders",
    "prompt": "You are Sarah from Bright Smile Dental. Call to remind the patient about their check-up tomorrow and confirm they can attend.",
    "timezone": "Europe/London",
    "recipients": [
      { "phone": "+447111000001" },
      { "phone": "+447111000002", "variables": { "patient_name": "John" } },
      { "phone": "+447111000003" }
    ],
    "schedule_type": "schedule",
    "scheduled_date": "2026-06-15",
    "window_start_minutes": 540,
    "window_end_minutes": 1080,
    "window_days": ["mon","tue","wed","thu","fri"]
  }'

Body parameters

Field	Type	Required	Notes
`agent_id`	string	Yes	Agent used for all calls in this batch
`prompt`	string	Yes	The call purpose for every call in the campaign - what the agent should say and why it is calling. Per-recipient `prompt_override` replaces it for that recipient.
`name`	string	No	Display name for the campaign
`from_number`	string	Yes	The number to dial from. Must be a number you have imported and attached to this agent. Works on Twilio and Telnyx.
`recipients`	array	Yes	Recipient objects (see below)
`skip_invalid`	bool	No	Default `false`: reject the whole request if any phone is invalid. `true`: dial valid numbers only; invalid ones are listed in the response.
`schedule_type`	enum	No	`now` (launch immediately, default) or `schedule`
`scheduled_date`	date	If schedule	`YYYY-MM-DD` - the day the campaign becomes due
`window_start_minutes`	int	No	Calling window start, minutes since midnight (540 = 9:00am)
`window_end_minutes`	int	No	Calling window end, minutes since midnight (1080 = 6:00pm)
`window_days`	array	No	Allowed weekdays, e.g. `["mon","tue","wed","thu","fri"]`
`timezone`	string	No	IANA timezone the calling window runs in, e.g. `Europe/London`, `Asia/Dubai`, `America/New_York`. Invalid values are rejected with `invalid_timezone`.

Recipient object

{
  "phone": "+447111000001",
  "variables": { "patient_name": "Sarah" },
  "prompt_override": "Optional - replaces the campaign prompt for this recipient only"
}

All variables are automatically injected as context for the agent - you do not need {{placeholders}} in your prompt.

Calling window and timezone

Scheduled campaigns do not fire at midnight - they fire inside the calling window, in local time:

The scheduler checks every 60 seconds. A campaign that is due but outside its window stays scheduled and is re-checked each minute - it fires within a minute of the window opening.
The window runs in this priority of timezones: campaign timezone (if you sent one) -> the agent’s timezone -> Europe/London.
Resellers: your end-user picks their timezone in your app, you send it per campaign - their choice wins over the agent default.
Overnight windows are supported (window_start_minutes greater than window_end_minutes, e.g. 18:00-02:00).
No window set = the campaign fires when the date is due (legacy behaviour).

One campaign = one timezone. Calling recipients across multiple countries? Split them by region into separate campaigns, each with its own timezone.

Response

201 Created (schedule_type now launches immediately):

{
  "campaign_id": "batchcall_7f8fe206a5522cb7",
  "status": "running",
  "valid_count": 3,
  "invalid_count": 0,
  "invalid": []
}

With schedule_type: schedule the response returns status: scheduled and the campaign fires inside its window on the scheduled date.

Behaviour

Calls are queued and processed respecting your per-key concurrent call limit
Each recipient becomes one outbound call with its own call_id
Failed calls are logged but do not stop the campaign
Voicemail detection runs per call. The agent leaves a short message built from your prompt, then ends the call with ended_reason: voicemail_detected. See Voicemail detection to control or disable the message.

Errors

Code	Cause
`missing_field`	`prompt` missing - every campaign needs a call purpose
`invalid_phone_format`	One or more recipient phones are invalid. `error.details.invalid` lists each one with the reason. Resend with `skip_invalid: true` to dial the valid ones only.
`campaign_creation_failed`	`from_number` missing, not registered to your account, attached to a different agent, or a Telnyx number. Also `invalid_timezone` (bad IANA value). The message states the exact reason.
`campaign_launch_failed`	The campaign passed validation but could not be launched - usually no carrier credentials for the `from_number`. The campaign is marked `failed`.

Error response shape

Every error follows the same shape. On a rejected batch, error.details.invalid names each bad number and why, so you can show it to your own users:

{
  "error": {
    "type": "invalid_request",
    "code": "invalid_phone_format",
    "message": "1 recipient(s) have invalid phone numbers. Fix them or pass skip_invalid=true to dial only valid ones.",
    "doc_url": "https://docs.nixflex.com/errors/invalid_phone_format",
    "details": {
      "total": 2,
      "valid_count": 1,
      "invalid_count": 1,
      "invalid": [
        {
          "phone": "+44745357377",
          "reason": "not a real number for that country code - check the digits (wrong length, or an area/mobile prefix that does not exist)",
          "row_index": 0
        }
      ],
      "hint": "Fix the numbers or resend with skip_invalid=true to dial only the valid ones."
    }
  }
}

Numbers are checked against real numbering rules, not just E.164 shape. +44745357377 looks like a UK mobile but is one digit short, so it can never connect - it is rejected here rather than accepted and lost.

Launching a scheduled campaign

A schedule_type: schedule campaign fires automatically inside its window. You can also launch it manually with Launch batch.

API

Platform API

Create batch campaign

Request

Body parameters

Recipient object

Calling window and timezone

Response

Behaviour

Errors

Error response shape

Launching a scheduled campaign

​Request

​Body parameters

​Recipient object

​Calling window and timezone

​Response

​Behaviour

​Errors

​Error response shape

​Launching a scheduled campaign

Request

Body parameters

Recipient object

Calling window and timezone

Response

Behaviour

Errors

Error response shape

Launching a scheduled campaign