I received a phone call from a local number. They ...

I received a phone call from a local number. They asked for me, but refused to identify the company they were calling for, even by acronym. I said now was not a good time, and called back at lunch hour. I asked who they were (they answered the phone by saying "hello" then silence). The woman said Client Services. I asked, "Client Services for whom? Is this a business or the client service department for a business?" Her response, "we handle different business for different clients." I said "Obviously." and remained silent. After a moment/minute (it was an awkward amount of time but I don't want to sound like I'm exaggerating) she responded with "Client Services, Incorporated." Another pause. I asked what type of business is the company she is calling from. She obviously had caller ID because she asked for me, and said she couldn't answer any further questions about the type of business until she could verify who she was talking to. What legitimate business cannot say what type of business they are? If I call Taco Bell they can certainly tell me they are a restaurant. She got angry (angrier?) at that point and began yelling something. I don't know what, because I hung up.