They are dead beat collection.  
What ever they ask or say. Tell them you are not that person. Even though you tell them not to call you they continue to call.
All you can do is block those SOB's.
They have old dead collections try to collect

Person on phone was very rude and would not tell me why they were calling... Asked me what my birthdate was. Very shady.

Received a call from his number. Asked for me, but before I told him it was me, I asked who he was and where he was calling from. All he would say was "Josh from St. Louis".

Debt collector calling about a student loan that was never taken out. I've explained to them that I never had a student loan but they continue to call. I have seen a raise in 800 calls lately and not just from them. It's annoying the crap out of me.

When you call the number back, they tell you press 1 to make a payment on your account .  This seams to be a debt collector.  It never says the name of the company.

i hate these people. call at odd hours never leave a voice mail

Called once. No message left.

Same thing, called but no voicemail.  I have had an increase of calls from 800 numbers lately that do not leave messages.  I don't have debts out there anywhere, no idea why they are calling.  Maybe early summer is just a peak calling season.