Mike,
Great ideas. I've tried pretty much everything. I had pretty much everything isolated and was still experiencing strange line noise, dropped calls, etc.. Once things weren't adding up for me I decided to try a different ATA. So far, so good. Crystal clear. I'm just not sure why this wasn't offered up as a potential solution sooner. It could have saved us so much time and aggravation.

Thanks for your input everyone. I really appreciate it.