For those who may be experiencing problems connecting to certain Linksys routers such as the WRT54Gx4(SRX400), I have found what may correct your problem, as it corrected mine.
My WIP330 would see the network and try to connect but could not allocate an IP then disconnect, this would happen no matter what changes I made to the phone or the router including assigning a Static IP to the WIP330 and opening ports for that IP, until, I went into Applications and Gaming settings, went to the QoS setting and disabled the 802.11e QoS option. I went back at put the WIP330 back to DHCP mode and cleared the Port settings on the Router, all is great.
Afetr that my WIP330 connected and registered flawlessly, and I am using my Vonage softphone line on my WIP330 with no problems at all and great quality sound.
