Called but left no msg, does anyone have a clue what type of telemarketing it is?

IT'S A SCAM! THEY TALK IN SPANISH TELING U IF U HAVE PROBLEMS WITH UR MAIL I GOT THIS CALL TO AND HUNG UP BUT KEEP CALING.

They keep calling, talking only in spanish, asking for donations to a fund to teach spanish people english, but when you tell them to stop calling in english or spanish, they claim to not understand either language

yes, that is a company who wants you to pay them money for some material where they teach you english. Basically they are fishing for spanish speakers only and then try to sell them something.
I happen to speak both and have told them repeatedly to take me off their list and have also re-subscribed to the Do not call list but they ignore it.
Actually when I tell them that I signed up for the Do not call list they hang up right away, but then still keep calling.