Debt collector keeps calling me, but won't tell me what for

A user reports receiving repeated calls from a debt collector claiming to be from 'Americollect' using different numbers and unclear debt details. The caller provides a P.O. box and website but never specifies the debt's origin, amount, or the user's name, raising concerns about potential scams. The user avoids answering calls due to fear of identity theft and has found no resolution in online discussions.