>> they were annoyed about people being able to see part of their SSN
Part of? I worked for AT&T back when they merged with Cingular. We only asked for the last 4 over the phone, but the entire 9-digit SSN was shown in the app. Every single low-level employee had (has?) the entire SSN in front of them. Never dared tell a customer that little fact when they made a fuss over my having access to their last 4.
When I worked for t-mobile it was last 4 of the social unless the customer requests otherwise.
Few requested otherwise, and usually it was because they were annoyed about people being able to see part of their SSN.