The Comcast Business Wireless Gateways (model: Cisco DPC3941B etc.) have a configuration detail that must be enabled for proper E Street Voice Pilot operation.
This setting in it’s default state will often cause trouble with E Street Digital Phone service running through the gateway / modem.
To edit, access the device configuration on the LAN with Login credentials (Default):
Go to Advanced > Port Management
“Disable all rules and allow all inbound traffic through” is disabled by default, this must be enabled.
See the screenshot below for where this option should be “checked” and thereby enabled: