Yeah, phone men with no ID would draw immediate suspicions. They usually all have an orange handset hanging from their belt, or a laptop for diagnosing broadband connections.
I am willing to bet GSA handles their own internal wiring people also, so that is why they didnt get farther than the GSA employee.
GSA has a contract for that sort of thing. Most government offices of sufficient size have someone who knows something about WAHREN. It heps to be fum Georgia to talk about WAHRS.