Consume ASP.NET Webservice from PHP Pearl (Namespace issue)

[Remy]

We have an ASP.NET Webservice that our client would like to access
from PHP (with the PEARL toolkit).
Making requests works fine and for functions that only have a return
value (no parameters) everything is good.
But as soon as they try to pass some parameters, they are not
received. Problem seems to be the namespace.
ASP expects this (according to the Testsite:
<soap:Body>
<EchoDateTime xmlns="http://www.supertext.ch/webservices/">
<echo>2007-03-21T09:46:52.0427284-04:00</echo>
</EchoDateTime>
</soap:Body>

What I get is this:
<SOAP-ENV:Body>
<ns4:EchoInteger>
<echo>1</echo>
</ns4:EchoInteger>
</SOAP-ENV:Body>
And this does not work.

When I manually add ns4 to the echo parameter it works:
<SOAP-ENV:Body>
<ns4:EchoInteger>
<ns4:echo>1</ns4:echo>
</ns4:EchoInteger>
</SOAP-ENV:Body>

Anyway to make ASP understand the 2nd version or any other hints?

Thanks

Remy