Salesman at door

Yesterday we had someone with an AT&T Uverse shirt on come knocking at our door. We live in the Heather Ridge Subdivision in Richardson, Tx. We didnt answer the door and he left. However, it was reported that this person knocked on many doors asking for entry into homes to check their Uverse devices. No one let him in. Was this a legit service from a legit AT&T service tech? Please advise.