How to make a Ringless voicemails with Twilio and PHP

I am trying to leave a ringless voicemail using Twilio and PHP by first making a first call followed by a second call while immediately dropping the first so that the second goes directly into voicemail but this does not appear to work.

All the two calls are received, one after the other instead of the second going to the voicemail. What corrections can I make:
function drop_voicemails() {
require DIR . ‘/vendor/autoload.php’;

// Your Account SID and Auth Token from console.twilio.com
$sid = "";
$token = "";
$client = new TwilioRestClient($sid, $token);
$phone_no = ''; // Replace with the actual phone number to call
$from_no = ''; // Replace with your Twilio number

// First call to trigger voicemail
$call = $client->calls->create(
    $phone_no, // To
    $from_no, // From
    array(
        "method" => "GET",
        "statusCallback" => "https://example.com/voicemail.php?to_phone_no=" . $phone_no,
        "statusCallbackEvent" => ["completed"],
        "statusCallbackMethod" => "POST",
        "twiml" => '<Response><Pause length="1"/><Hangup/></Response>' // Short delay and hangup
    )
);

// Wait for a few seconds to ensure the first call is processed and goes to voicemail
sleep(3);

// Second call to drop voicemail with inline TwiML using your own MP3
$call2 = $client->calls->create(
    $phone_no, // To
    $from_no, // From
    array(
        "twiml" => '<Response><Play>https://example.com/uploads/message_1_1003.mp3</Play><Record maxLength="20" action="https://example.com/handle-recording.php"/><Hangup/></Response>'
    )
);

echo "Voicemail left successfully.";

}

I tried reducing and increasing the sleep time but it does not appear to work. Is there a better solution since I am working with numbers that cannot receive an SMS?