Phone number is very important for the purpose of verification especially if you apply for payday loan online. (myfinancekits.com)
An investigation is a «a searching inquiry for ascertaining facts; detailed or careful examination», which suggests a wider and more complex aim than an audit which is «to examine (accounts, records, etc.) for purposes of verification.» (blackhobyah.net)
This is merely a supposition but perhaps the acceptance of a faxed document with a signature is deemed more acceptable because there is an assumption that there exists a «hard - copy» of the document with a «penned» signature ready to be used for the purposes of verification and / or authentication. (slaw.ca)