Hi Narottam
What you did in Step 1 and 2 is to create a service provider in your ECC system - it can only be used to receive into your ECC system and not to send out.
If the HCI system has access to PI, you can define a service interface in PI ESR and import it into an HCI iFlow. After building and deploying the HCI iFlow, you can download the WSDL from it and use it to generate a consumer proxy in ECC. The WSDL will also contain the SOAP endpoint to call HCI.
Rgds
Eng Swee