What exactly constitutes a pre-qualification request?
Review the Commentary to Reg. B, 1002.2. It discusses what is and is not an application. Basically a pre-qualification is the consumer saying I'm thinking about doing this so about how much money can I borrower. I know that's an over simplification. Your FI should have an application process in place.
How do you document permissible purpose for telephone pre-qualifications and/or applications where there is no signature on an application?
That is an internal decision but IMO the best practice is to have a short "telephone app" the LO is required to complete with the name of the consumer spoken to, the purpose of the inquiry and the date of the inquiry.
The norm around our shop is no permissible purpose without a signature (especially for a prospective customer with no existing relationship) because if a customer were to come back on us and say they did not give us permission to pull their credit, how can we justify without having their signature?
If this is your norm then you best be requiring it for all applicants and not leave it to the LO's discretion. Otherwise you are facing fair lending issues for treating applicants differently.
Unless state law requires a signature the FCRA does not require one for you to have a permissible purpose. You just need to be able to demonstrate through you application process that you only obtain a consumer report when a consumer has requested credit.
The opinions expressed are mine and they are not to be taken as legal advice.