curl --request POST \
  --url https://{appId}.api-{region}.cometchat.io/v3/messages/{id}/thread/subscription \
  --header 'apikey: <api-key>' \
  --header 'onBehalfOf: <onbehalfof>'

import requests

url = "https://{appId}.api-{region}.cometchat.io/v3/messages/{id}/thread/subscription"

headers = {
    "onBehalfOf": "<onbehalfof>",
    "apikey": "<api-key>"
}

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

print(response.text)

const options = {method: 'POST', headers: {onBehalfOf: '<onbehalfof>', apikey: '<api-key>'}};

fetch('https://{appId}.api-{region}.cometchat.io/v3/messages/{id}/thread/subscription', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://{appId}.api-{region}.cometchat.io/v3/messages/{id}/thread/subscription",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_HTTPHEADER => [
    "apikey: <api-key>",
    "onBehalfOf: <onbehalfof>"
  ],
]);

$response = curl_exec($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://{appId}.api-{region}.cometchat.io/v3/messages/{id}/thread/subscription"

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

	req.Header.Add("onBehalfOf", "<onbehalfof>")
	req.Header.Add("apikey", "<api-key>")

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://{appId}.api-{region}.cometchat.io/v3/messages/{id}/thread/subscription")
  .header("onBehalfOf", "<onbehalfof>")
  .header("apikey", "<api-key>")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://{appId}.api-{region}.cometchat.io/v3/messages/{id}/thread/subscription")

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

request = Net::HTTP::Post.new(url)
request["onBehalfOf"] = '<onbehalfof>'
request["apikey"] = '<api-key>'

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

{
  "data": {
    "success": true
  }
}