archiving text messages on 3G

Access carriers website to log number of txt to and from.
Contact carrier about what they are able to provide to you about transcripts if anything. May need court order.

Hire a good lawyer who will obtain a court order to do so. If you try doing this on your own, without good legal representation, you will find yourself with bigger problems than your wife having an affair.

AT&T, like most carriers, wipe SMS's from their system after about 48hrs...too much data to store. Follow my advice, get a good lawyer, he/she will obtain a court order forcing AT&T to retain the SMS in question. If you try doing this yourself, believe me, you will end up with worse problems than your wife having an affair.

AT&T does NOT retain text messages at all, just like they do not retain cell phone conversations. And unless you are a law enforcement agency with a valid search warrant you will not be able to obtain any private information from AT&T.

How would key stroke software on your phone accomplish anything?