Netgear FVS 338

Netgear FVS338.

Downgrade the firmware to version 3.0.4-19.
This version does not have SIP/ALG support.
This *should* allow you to register properly.

Note:
There is a Beta version of the firmware: 3.0.5-27.
This version has a SIP tab which allows you to turn off the SIP ALG.