The firmware version 3.xx has problems with ATA-Adapters because the Firmware should not be "100% Sip aware". If you try to register by dialing there's always the same error: "SIP/2.0 479 Please don't use private IP addresses" With the older version 2.xx VOIP should work. Unfortunately I have a Hardware Version 2.2 and I can't use older Firmware. see also here: http://www.linksysinfo.org/modules.php?name=Forums&file=viewtopic&t=1423&highlight=sip+aware If you look into the Version Information you see that there where made fixes with VOIP. Perhaps there the problem begins... Firmware 3.01.3 - Updated wireless driver - Supports hardware version 2.2 (cannot downgrade to previous versions) - Resolves issue with VoIP adapters - Resolves issue with long domain names Does LinkSys knows from the problem? Are there any plans to fix this problem?