I have received several calls on a daily basis from this number (812-602-0965) to my ATT work cell phone - No Message Left - and No one on phone the one time I answered

This number has been calling once a day for 2 or 3 days in a row, one or 2 weeks every month for the last year and a half. Sometimes they will leave a blank voicemail of 30-50 seconds...nothing at all audible. Calling back gets an automated "none of our reps are available; we'll call you back within 24 hours." Since they're calling on my business numbers suggests they're some kind of B2B telemarketer.