How to consume a customer WebService which is outside of SAPs network

Hi,

How to call a WebService-Provider which is running in a foreign/customer network? My WebService Consumer I created on a Netweaver AS 7.11 ABAP which is running in SAPs corporate network.

I think I have to use a Proxy-Server. But how I do that and what are the settings for the Proxy-Server?

Thanks,

Christian