If you have the messages in a backup you can restore that backup to your phone (which will overwrite everything on your phone) or get one of the many iPhone backup extractor programs available for your computer. But note that if you have backed up since then the most recent backup has overwritten all previous backups unless you archived the backup in question (available only on a Mac) or you have a backup of your computer dating from the time you made the backup.
AT&T has your call history; they are required to keep it by law for at least 18 months, and you can view it in their user portal or in the My AT&T app. It’s a little hard to find, but it’s there. Look for “view usage logs” or equivalent.