I just wanted to chime in.... I upgraded to a Netgear CM1150v modem with voice and use Xfinity. My phone network (and ethernet network) go through an On-Q network box that has its own power source. I could not receive incoming phone calls when I installed the new modem. I had a dial tone and could make outgoing calls but callers would receive the message "The mailbox ..is not in service". So it would not distribute the ring or the signal through the network. I was able to plug a phone directly into the modem and receive calls. Comcast tried to help but nothing changed. After scouring the boards and messing with a lot on the On-Q box, the solution came down to using Tel2 (and not Tel1) out of the modem. Who knows why.... just thought I would put it out there for anyone else with the same problem.
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