Have had several other calls the last week from other 801-883- numbers, I assume they are all from the same organization.  Never leave a message, they do not respond when I answer the call.

Same here. Random final four numbers, calls at random times of day, number is either invalid when redialed, or rings with a hangup. Answered the call one time and was hung up on. What really sucks is that the 883 prefix is also the prefix for my company phone numbers, so I cannot simply block all 801-883- numbers as doing so would block me from all business related calls. I really hate these guys!