I’ve read through a few of the messages here and we’re having a similar problem. I have a Polycom phone that was working great with my cable modem thru the DMZ.
I switched over to ADSL (PPPoE), and set the DMZ to the same IP as the phone. I can dial out fine, however it doesn’t work for incoming calls. I read where some folks had to do port forwarding to get it to work.
Any ideas or suggestions? I’m runing a Linksys router by the way.