Intercompany Billing

Hi,

We would like to automate the posting of AP documents from AR documents for interco transactions within the same SAP system.

I have read some of the online resources such as:

http://wiki.sdn.sap.com/wiki/display/ERPLO/Inter-Company+Billing+-+Automatic+Posting+To+Vendor+Account+%28SAP-EDI%29

http://wiki.sdn.sap.com/wiki/display/ERPLO/INTER+COMPANY+BILLING

However, I kept reading that I need to set up partner profiles for EDI processing. Is it necessary? I thought EDI is used for external system interfacing?

Thanks for any advice!