VOIP static

I just tried the Vonage VOIP telephone service. While the sound quality is ok, there is static on the phone signal generated by the linksys PAP2 adapter (and the phone is connected directly to the PAP2 - not house wiring, and tried multiple hard wired and wireless phones that work ok on the bell line). The static doesn't go away when the PAP2 is disconnected from the LAN, so it seems the PAP2 is generating the noise. So dumb question, don't know how the PAP2 does D/A conversion, but seems strange that it would make this noise since it is powered from a 5V DC adapter. Is it possible that the noise is due to a cheap or bad AC/DC converter? What else might cause this?