I was at a different telecom a couple years back and legal handed down a ruling that we couldn't keep things beyond two years, even though we were research instead of billing. Research was the last group at the company to have to delete all that stuff, and we only had space for five years anyway, and even that was stripped down to 10% of its original data. However the researchers felt very safe in assuming that since the government has all of the data reflected off the antenna base station switches through its own network, there's no way they're deleting anything.

It's weird that at&t had to give them that data, unless you assume that up til now they had access to the nsa's copy and now the justice department says they have to have their own.