$ch = curl_init();
curl_setopt_array($ch, array(
CURLOPT_URL => 'https://bips.me/api/v1/invoice',
CURLOPT_USERPWD => 'apikey',
CURLOPT_POSTFIELDS => 'price=100¤cy=USD&item=TEST&custom=' . json_encode(array('order_id' => '1')),
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HTTPAUTH => CURLAUTH_BASIC));
$url = curl_exec($ch);
curl_close($ch);
header('Location: ' . $url . '/iframe');