WeWork (a shared office concept) in Denver was a head scratcher. We kept running into cell phone signal interference that we could NOT trace. After relentless troubleshooting, we finally discovered two issues. The first was a leaky DAS (Distributed Antenna System - it's the communication required to be in place for first responders). The second issue actually originated in the neighboring high-rise building that was under construction! They had secured their network with filters that were blocking our cell signal next door. Perseverance paid off and we were able to deliver extraordinary cell signal to the WeWork offices.