Great. As if telecoms can be trusted with customers' id. AT&T left my name, address, social security etc in an improperly secured database for others to have, and they tried to open accounts with it; they had retained the information after I closed my account, and they denied the information was coming from them for years before they finally admitted it and gave us all a quarter to call someone who cares and a year of credit monitoring.
I have heard very little about AT&T's actual telecom services, but my god have I heard about their billing department. I daresay the only departments in more of a shambles than their billing one is... well. A lot of Microsoft lately.
T-Mobile also has had numerous breaches. And Verizon sells your location data as I recall.