Before trying to log in to the phone’s web portal you must enable the web interface:
Press Home -> Menu -> Settings -> Network ->Embedded web -> On
To find the IP of the phone do the following:
Press Home -> Menu -> Settings -> About phone -> Status
The administrator credentials for the Panasonic KX-UT670 is:
username: admin
password: adminpass
VoIP4EA 
Worked Thank you.
do you know how to configure that phone for TeleVantage 7.5? I have it almost working but no cigar. the phone rings but can’t talk. external calls work fine but internal calls are not working.
Thank in advace.