These notes have been taken from this blog post and trial-and-error.
After connecting the KT-UX113 Panasonic VoIP (SIP) phone to the Ethernet and, assuming your network has dynamically assigned it a DHCP address, do the following.
You’ll see an error displayed:
Connection error (90001)
Check server and set it.
Press Setup. Press Enter to select “Information Display”. Scroll down using the down arrow once to see your IP address:
Now press Back. Then press the down arrow to select “Network Settings” and press Enter.
Scroll down to select “Embedded web”. Use the down arrow to change this setting to “On”.
Press Enter. You will hear a long beep.
Now in your web browser navigate to http://192.168.1.19/ (or whatever the IP address was that you saw your phone displaying under “Information Display” -> “IP Address”.
You will be asked for a username and password. The defaults are user:admin, password:adminpass.
If you do not log in fast enough the embedded web server will switch off and you will have to enable it again on the phone.
You should see the following web page:
Panasonic KX-UT113 Web Page On First Login
One of the first things you may wish to do is upgrade the firmware, the latest for each country can be found here. (It so happened that the phone I purchased off eBay in the UK already had the latest firmware). Firmware can be loaded through the web interface from the “Maintenance” tab and “Local Firmware Update” menu option.
For some reason it appears the “encryption” option has to be selected in order for the firmware to actually be applied.
Uploading new firmware
The process can take around 2 or 3 minutes for the firmware file UT11x12x-01.302_HW1.fw.