Hello. I need help from professionals ;)

I'm facing a really strange problem on Nokia 6070 phones using HEADER("Location: ...") within a biiling API. While it works fine on every other device, exactly here it does not perform the redirect, giving me an 405 - BAD REQUEST!?

The billing interface receives and returns XML data submitted by the POST Method. I am using cURL in php for that reason.
I send the first identificacion to the billing interface and after having received the SUCCESS, the device needs to be redirectet to a given URL on the billing server.

So far it looks like this

if($this->identify()) {
// Identify was successful - we received the redirect-url in our result
session_write_close(); // close session file
HEADER("Location: ".$trans->redirect_url);
exit();
} else {
// Identify faild
return false;
}

The result from a cURL operation returned SUCCESS and the $trans-redirect_url is set. On Nokia6070 it stops printing Error 405 ...
I know what HTTP ERROR 405 means, but I do not understand why it only occurs on this device. Now I'm stuck. I'm not sure wether it has something to do with the Configuration of our Apache Webserver or something specific in this device.

The redirect URL suports the POST method.. Is it possible that the device submits in GET by default? IF so, is it possible to add Headers before doing the redirect itself? Has anyone experiencd similar Problems?

I woul appreciate any hint that helps going further ....

Regards