Scam ,that's why they don't leave messages ,afraid of the cops ,for being crooks,if you don't nko the number don't pick,up the phone if you don't no the number,if you do tell them you are recording them,like a roach they will run and hide.
Hello can I speak to so and so.... I didn't recognize the number and said "Not available at the moment can I leave them a message?" And the called said "I'll call back later". Never said who he was or why he was calling nor from where.