Григорий Коваленко

$prms = array(
    "id" => id_deal,
    "fields" => array(
        "id_field" => 'value',
    ),
);
$prms = json_encode( $prms );
$result = bx24( $prms, 'crm.deal.update' );

function bx24( $params, $type, $portal = '***', $admin_id = '***', $secret_code = '****' ) {
$queryUrl = 'https://' . $portal . '.bitrix24.ru/rest/' . $admin_id . '/' . $secret_code . '/' . $type;
$params = json_decode( $params, true );
$queryData = http_build_query(

		$params
	);

	$curl = curl_init();
	curl_setopt_array( $curl, array(
		CURLOPT_SSL_VERIFYPEER => 0,
		CURLOPT_POST           => 1,
		CURLOPT_HEADER         => 0,
		CURLOPT_RETURNTRANSFER => 1,
		CURLOPT_URL            => $queryUrl,
		CURLOPT_POSTFIELDS     => $queryData,
	) );

	$result = curl_exec( $curl );
	curl_close( $curl );

	return json_decode( $result, 1 );
    }
?>