Rare in the sense that they are not often discussed here. They are very similar to the OBi202 except that they don't support GoogleVoice and GoogleVoice is perhaps what attracts most purchasers (at least in the US).
The 302 you bought from Amazon should not be locked in any way. I guess you initially configured the device using the basic mode on the portal and then found there seemed to be far more controls on the local GUI.
You can either disable remote provisioning - local GUI, System Management, Auto Provisioning, Obitalk Provisioning, Method = Disabled and do everything locally. Or use the Expert Mode on the portal which has almost identical config options.