I received a suspicious voicemail message from 800-852-1181, went online and saw your post, and also found the website "myfedloan.org after a search for "Fed Loan Servicing".
If PHEAA is a client of yours as you say, do your client a big favor and tell them to improve their website and their computerized phone voicemail messages. Their phone message sounds like a total scam. There is nothing immediately apparent from their website to assure people who have been called as "references" that the call is legitimate. Their voicemail message should refer people to their website for more information, and should refer to a webpage that contains a callback number and further details of legitimacy.
For now it still sounds like a scammer is trying to steal personal information by pretending to be some servicer of federal loans.