Windows 7: Massive packet loss after VOIP install

I have/had a fairly typical home desktop/cablemodem setup (no router, just direct connection of modem to PC via ethernet cable). Today I had digital phone service installed, so they replaced my small "coaster" modem with a huge UBEE modem. They kept all the other hookups and connections the same, as far as I can tell.

However, now I am getting between 60-95% packet loss on line test websites that have always consistently shown 0% packet loss with the old modem. Raw speed tests seem unchanged (10 MBit). If I understand the modem diagnostics page, the signal levels are OK. Surfing the web works, but gaming would be out of the question with this kind of packet loss.

Any idea why adding VOIP would cause massive packet loss? What could be the problem? Thanks for any ideas.



Edit: packet loss seems to be related to the UBEE modem/router firewall settings. If I turn off the firewall, the measured packet loss goes to zero. I guess that "resolves" this issue.