Restore from backup, then use SSH or ifunbox or iphone explorer to grab the sms.db file out of var/mobile/library/sms. Then restore and set up as a new iphone, and put that file back in the spot mentioned. You'll need to change the permissions to get it to work, the easiest way is to use ifile on the phone and set to full permissions (Read, Write, Execute, easy to do and is obvious when you access the file through ifile on your phone). You'll then have the texts on a set up as new iphone.