You are either bridge tapped, or you have heavy interference at around 2.4 MHz
Either way, assuming the home run Cat 5 is wired properly, an outside line (I&M) technician will be needed to be dispatched to clean up that pair and eliminate the tap and/or the interference
I would suggest contacting AT&T Tech Support via 800.288.2020 to schedule a technician visit (ask Mr Voice Response for "U-Verse Technical Support"), or contact AT&T's Social Media Support team by either posting in the AT&T Direct forum on this site (which requires site registration) or via email to email@example.com.
The Social Media Support team needs your name, address, account number & account passcode, summary of the issue, a link to this thread, past history of trying to get the trouble resolved with previous contacts to Tech Support and/or Technician visits, and good contact information to reach you (phone, email, etc)
Thanks, I've called AT&T and we'll see what they can do. Honestly though, I fear many many more calls and hassle and service trips before getting any resolution. If there is anything I might be able to try I'm certainly willing to give it a try... Just not sure what if anything that might be!