Name Not Found on caller ID.

They have called me twice in the past 2 weeks and I answered one time at which time they quickly hung up.  I attempted to file a complaint with the National Do Not Call registry but their system will not accept my complaint, stating that the telephone number I entered is invalid.  Guess I will keep ignoring this call.

this number has called today twice in the hour, has called other days as well, have no idea who they are

this number called last week, weird number, who has a number with all zeros, very strange

GOT A UNKNOWN CALL FROM 2390000000...DONT NO WHO IT IS ..WOULD LIKE TO KNOW