Web Service to RFC ICO Scenario

Hi experts,

I want to implement a Web Service --> PI --> RFC in SAP PI 7.3 with an Integrated Configuration Scenario and using Web Service Security. Is that possible??

I have tried a sender communication channel WS and I can not use in my ICO.

With SOAP sender communication channel I can use it in my ICO, but it doesnt allow me to validate with user/password.

I've got another question, do I have to create a Sender Agreement and publish it in SR??

Many thanks