I just received a phone call from "Jason at AT&T" claiming there has been an outage in my area and he just wanted to check on my service. Considering I have a cell phone that is not affected when my local Verizon/Frontier service goes down, I was immediately suspicious coupled with the fact that AT&T NEVER makes such calls.
The clincher was him offering to send me a text validating that he had called me that would include a 15% discount off my next invoice. Again, two things AT&T would never do.
I asked him where he was located (he had a slight South Asian accent), he could not tell me, and then clearly he looked up my information and said "Texas." I said, "Where in Texas" and he pronouced the name of my city WRONG.
When I told him I could not validate he was from AT&T (the number he called from was ***) and to send me an email, since I would never click on a link in a text from someone I didn't know, he hung up on me. 
[Edited for privacy-please do not post personal or unique information such as but not limited to full names, employee ID numbers, email addresses, phone numbers, account numbers, etc.]