SIP UC-One

I am a new Comcast Customer.   My wife's company uses software called UC-One for SIP Calling, but it will NOT work when I connect to our Comcast Internet.   We've tried:

3 different Computers (Windows and MAC)(They all work PERFECTLY when I connect to our Consolidated Service)

2 different routers (Motorola and Arris)

Enabling all Ports that UC-One suggests

Ensuring SIP is enabled (1000 times, and disabling it)

Disabling machine level firewall

Running devices in a DMZ to eliminated modem/router firewall

Contacting Motorola Support (they were baffled too, confident it should be working)

Contacting Comcast Support (useless, teir 1 tech)

How can I get ahold of a capable engineer at Comcast to get SIP working?