Hi,
You can use web services, once the data is encrypted in SAP Netweaver PI to pass on the messages to the banks.
Kindly note that SAP BCM comes along with SAP Integration Package for Swift which in turn will send the messages to Swift Alliance Access / Gateway and then to the banks. This will help you in reducing costs as you will have a single channel communication to all the banks you deal with. It will also reduce the number of proprietary payment standards and bank-specific e-banking products and setting up a single communication channel to SWIFT Net.
Warm regards,
Akhil Poddar