But from their page Vpayments is already integrated with CABS, CBZ, POSB and Trust banks. The merchant has to interface with Vpayments and his customers can then be from any of those banks...
The merchant has to sign up with a bank, but this is so he has an account for the money to be deposited into, he does not need to integrate with the bank, he only needs to integrate with Vpayments using the API they provide in their documentation.