This sounds like debt collection. Could be the usual US lawbreaker or (I strongly suspect) a fake collector from South Asia. Try to get a business name and share it with the readers. By federal law this name cannot be withheld.
Learn how to exercise your FDCPA rights as an alleged debtor at FTC-dot-gov.
Make it plain to your employer that these calls are meant to abuse and harass you and are not ''personal'' since you would not have invited them. If a ''very detailed message'' reveals to others that you are supposedly liable for some debt, that violates the law I just cited.