Wired news has the juicy excerpts from former AT&T technician Mark Klein's deposition in the EFF class-action lawsuit.
The wired article is here
One of the better segments is this description of what is in the secret room noted in an earlier diary. The secret room contained a branch of the main phone and data trunks (including anything on AT&T Worldnet service) that had a side effect AT&T engineers had to work around - it degraded signal quality:
This problem is solved with "splitters" which literally split off a percentage of the light signal so it can be examined. This is the purpose of the special cabinet referred to above: Circuits are connected into it, the light signal is split into two signals, one of which is diverted to the "secret room." The cabinet is totally unnecessary for the circuit to perform -- in fact it introduces problems since the signal level is reduced by the splitter -- its only purpose is to enable a third party to examine the data flowing between sender and recipient on the internet.
Without a doubt, AT&T and SBC were active participants in the whole TIA program (AT&T had equipment from a prime TIA vendor in these splitter rooms) and obviously continued on with the recent phone records scandal, despite their denials.