We transfer to two different banks using two different methods. For payroll we use FTP and send the data in the format the bank needs.
For the other, the file is deposited in a global mailbox where the bank retrieves it. Of course, this method requires you have a mailbox account and password.
These processes run on the mainframe under zOS 1.3.
Don’t know if this helps or not, but I’d be happy to send examples.