The CYT unlocker won't do anything for you because it's specific to the Vonage firmware 1.00.xx
Is there anything in the Restricted Access Domains field ? (under the VoIP section, System tab). That could prevent it from registering with other services.
If not, clear the VoIP passwords then do a factory reset (hold the reset button down for 8-10 seconds, until the lights start flashing). See if it still requires a password for the Admin user.
If it still requires a password, the unit is probably customized to CIK and you have to remove that customization in order to make it work. A different firmware won't help you. You have to erase the flash partition that holds the customization data. This could be done in a couple ways: if you can enable SSH, login to it via SSH, then run the command
dd bs=65536 if=/dev/zero of=/dev/mtd/9
Then do a factory reset.
If you can't enable SSH (can't remember if it's available in that firmware version), you can install Firefox with the Developer plugin, then go to the Diagnostic page / Ping, remove maximum lengths then enter this in the address field and click Ping:
127.0.0.1 & dd bs=65536 if=/dev/zero of=/dev/mtd/9
Again, you need to do a factory reset after this.