Nixflex - AI Voice Platform for Building AI Phone Agents

List calls

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

<?php

$curl = curl_init();

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

$response = curl_exec($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"

	req, _ := http.NewRequest("GET", 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")

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

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

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

GET

calls

List calls

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

<?php

$curl = curl_init();

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

$response = curl_exec($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"

	req, _ := http.NewRequest("GET", 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")

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

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

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

Returns your calls, newest first. 50 per page by default - page through the rest with limit and offset.

Request

curl https://api.nixflex.com/v1/calls \
  -H "Authorization: Bearer KEY_ID:KEY_SECRET"

Query parameters

Parameter	Type	Default	Notes
`limit`	int	`50`	How many calls to return. Hard-capped at 200 per request - a higher value is reduced to 200 rather than rejected.
`offset`	int	`0`	How many calls to skip. Combine with `limit` to page back through older calls.

# the 50 most recent
curl https://api.nixflex.com/v1/calls \
  -H "Authorization: Bearer KEY_ID:KEY_SECRET"

# calls 101-200, newest first
curl "https://api.nixflex.com/v1/calls?limit=100&offset=100" \
  -H "Authorization: Bearer KEY_ID:KEY_SECRET"

The response is a bare array, not an object with a total or has_more. Page until you get fewer rows back than you asked for.

Response

200 OK returns a JSON array:

[
  {
    "call_id": "CA1234567890",
    "agent_id": "agent_125207e452f8714a",
    "call_direction": "inbound",
    "from_number": "+447386172392",
    "to_number": "+447446466847",
    "call_status": "completed",
    "start_timestamp": 1784987006751,
    "end_timestamp": 1784987048847,
    "answered_at": 1784987011051,
    "duration_ms": 146000,
    "ended_reason": "agent_hangup",
    "transcript": "AI: Good morning...",
    "call_summary": "Caller booked a check-up",
    "caller_sentiment": "happy",
    "call_successful": true,
    "extracted_data": {},
    "bookings": [],
    "recording_url": "https://storage.nixflex.com/recordings/CA1234567890.mp3",
    "voicemail_detected": false,
    "created_at": "2026-05-17T03:45:12Z"
  }
]

Response fields

Field	Type	Notes
`call_id`	string	Unique ID for the call
`agent_id`	string	The agent that handled the call
`call_direction`	string	`inbound` or `outbound`
`from_number`	string	Caller’s number, E.164
`to_number`	string	Number that was called, E.164
`call_status`	string	Final status of the call
`start_timestamp`	int	When the call was created, epoch milliseconds. On an outbound call this is when the carrier was asked to dial, BEFORE the phone rang.
`end_timestamp`	int	When the call ended, epoch milliseconds.
`answered_at`	int or null	When the call was ANSWERED, epoch milliseconds. `null` on inbound calls and on calls that predate this field - see the note under `duration_ms`.
`duration_ms`	int	Time connected, in milliseconds - measured from answer to hangup, and the number you are billed on. Ring time is NOT included, so this will not equal `end_timestamp` minus `start_timestamp` on an outbound call.
`call_type`	string	`inbound` or `outbound`. Same meaning as `call_direction`; both are returned.
`voicemail_detection_method`	string or null	Which detector found the voicemail: `twilio_amd`, `telnyx_amd` or `llm_transcript`.
`amd_result`	string or null	What the carrier’s machine detection reported, e.g. `human` or `machine_start`. Only present when machine detection is enabled.
`call_reason`	string or null	Reason extracted from the conversation, when the agent captures one.
`caller_name`	string or null	Caller’s name, when known.
`ended_reason`	string	Why the call ended
`transcript`	string	Full transcript. Included in this response
`call_summary`	string	AI-written summary
`caller_sentiment`	string	`happy`, `neutral`, or `frustrated`
`call_successful`	boolean	Whether the call met its goal
`extracted_data`	object	Fields pulled from the call, per your agent’s extraction settings
`bookings`	array	Appointments booked during the call
`recording_url`	string	Link to the MP3, or `null` if recording is off
`recording_duration_s`	int	Recording length in seconds
`voicemail_detected`	boolean	Whether the call reached a voicemail
`campaign_id`	string	Outbound campaign this call belongs to, or `null`
`avg_latency_ms`	int	Average response latency during the call
`created_at`	string	ISO 8601

duration_ms is time CONNECTED, not dial-to-hangup. Ring time is excluded, so it matches what your carrier bills you and it matches the recording length. On an outbound call start_timestamp is when dialling began, so end_timestamp - start_timestamp will be LARGER than duration_ms by however long the phone rang. Use answered_at if you want the ring time: answered_at - start_timestamp.

The response includes internal fields that are not part of this contract. You will see id, api_key_id and system_prompt_used in the JSON. They are yours, but they are engine plumbing rather than API surface - do not build against them, as they may change or be removed without a version bump.

Older calls stay reachable with offset, but call data is deleted after 90 days - see Data retention. To keep full history, subscribe to the call.completed webhook and store each call in your own backend as it arrives.

Fetch one call by ID with Get call.

​Request

​Query parameters

​Response

​Response fields

Request

Query parameters

Response

Response fields