[ceejayoz]

AT&T and the NSA are not the same thing.

AT&T is almost certainly not storing every text message long-term. The NSA likely is. It wouldn't be surprising if that's via a direct PRISM-style integration, but it still means subpoenaing AT&T for old texts is likely to not be productive. (As it was not productive in this particular case.)

Subpoena the NSA and they'll say "no, for national security reasons".

[shadowgovt]

I'm not even sure we can extrapolate that the NSA is storing anything like every text message long-term (as opposed to metadata, or samples, or the full transcripts of individuals targeted for investigation, or a machine learning trained weights set to flag messages that indicate someone should go on the targeted-for-investigation list).

6 billion text messages are sent per day in the US. That's about the volume of Google web searches, and I know from experience Google doesn't have the capacity to log every search or the logs of evaluation of every search. If Google lacks the capacity, I suspect the NSA lacks the capacity.

[GauntletWizard]

Google absolutely does have the capacity to log every search query, and does - and I say this as someone who has worked with that dataset, if only for training purposes.

6 billion SMS messages, at a max length of 160 characters, is 1 terrabyte of raw text. I think that the NSA has the cash to shell out $100 for a new 1TB hard drive every day... (not even including compression, of which it is highly, highly compressible)