Update Android version on Panasonic KX-UT670
Actually, reading the developer manual, it seems you can't


  Applications developed by using KX-UT670 APIs are exclusively for use with the KX-UT670. 


That, IMHO, implies they have it's own API, thus you have to develop in this API to make an app AND you cannot update, or upgrade Android version in the device. 

Yes, it is Android 2.2 version, but not an open one... :(