The information the caller had in seeking to remind me of an overdue bill was correct except for the offsetting credit.  However according to UPS the number 800-305-9712 is not UPS billing nor UPS account receivable. So how did Adalpho (the callers' name) obtain the account information?

Caller ID was blank. Heard part of a recorded message, then a female voice with a slight foreign accent said hello a few times, rattled off the phone number, and said "Thank you for shipping UPS."

Someone with an accent left a voice message, said they were with the UPS Accounts Receivable Dept. Left what was supposedly my shipper number,  and 800 305 9712. Obviously a scam. I played along for a while, rattled their chain, but would not give my personal info. Even asked to talk to a superior, and did. So this is a big scam. Probably wanted bank account numbers, routing numbers, to drain my account. Called the real UPS, they said they don't make calls for payment.

Claimed they were from UPS accounting office. I guess they thought this was my first rodeo.

Got an anonymous call allegedly from UPS accounts department that left this number as a callback. Caller had a very heavy female Pakastani or Indian accent.