Here is an interesting thought. WiFi phones lack browsers. Hence they can't be used with authenticated hotspots even if you have legit login credentials.

You can use N770 and other tablets to spoof the MAC ID of the phone, connect, authenticate and then step down and allow the phone to take over. I tested this technique on a recent cross country trip and it works quite well.

MAC ID faking instructions for Linux and Windows.

Or just use the tab as a SIP or skype phone?