Firebase FCM from PHP the easy way. Send payload as desired. Returns execution result. Just a gist, no production code.

send-fcm.php

<?php
$deviceToken = $_POST['dt'];
$body = $_POST['b'];	

if (empty($deviceToken)){
	die ("nothing to do, no device. exit");
}
#API access key from Google API's Console
define( 'API_ACCESS_KEY', '' );
#prep the bundle
     $msg = array
          (
		'body' 	=> $body,
		'title'	=> 'notification',
             	'icon'	=> 'myicon',/*Default Icon*/
              'sound' => 'mySound'/*Default sound*/
          );
    $dataMsg = array
          (
		'phone' => array("no" => "12", "label" => "xxx"),
		'data1' => 'ggg',
		'data2' => 'hhhh'
          );

	$jsonArray = array
			(
				'to'		=> $deviceToken,
				'notification'	=> $msg,
				'data'	=> $dataMsg
			);
	
	$headers = array
			(
				'Authorization: key=' . API_ACCESS_KEY,
				'Content-Type: application/json'
			);
			
echo "<hr><code><pre>";
echo json_encode( $jsonArray );
echo "</pre></code><hr>";

#Send Reponse To FireBase Server	
		$ch = curl_init();
		curl_setopt( $ch,CURLOPT_URL, 'https://fcm.googleapis.com/fcm/send' );
		curl_setopt( $ch,CURLOPT_POST, true );
		curl_setopt( $ch,CURLOPT_HTTPHEADER, $headers );
		curl_setopt( $ch,CURLOPT_RETURNTRANSFER, true );
		curl_setopt( $ch,CURLOPT_SSL_VERIFYPEER, false );
		curl_setopt( $ch,CURLOPT_POSTFIELDS, json_encode( $jsonArray ) );
		$result = curl_exec($ch );
		curl_close( $ch );
#Echo Result Of FireBase Server
echo $result;
?>