Never call them back! If they are a legitimate company, they will leave a message. You have nothing to gain by calling back. All you are doing is confirming they reached a valid number. Or, they may have spoofed the number and you could be calling an innocent party.
Number called 4 times with no messages. My phone registered Dallas, Texas. Will be blocking due to the reports or scams, fraud, and unknown purpose. Thanks all for the input.