Some banks assign ID numbers tro the merchants who routinely call in. Our bank (small, rural) doesn't, yet. We will still verify whether funds of a certain $ amount are available or not, but that's it.
We did disconnect the merchant verification feature on our phone response system 2 years ago, because it didn't limit the number of inquiries on an account. We felt this was an unacceptable security risk.
Can you discuss what kind of fraud issues you're encountering?