The following information is to assist our users in upgrading the firmware in their Cisco SPA-504 phone.
The latest SPA-504 firmware we have is version: 7.6.2g
(NOTE: Most Cisco phones won't let you jump over several version of firmware to install the latest. If your firmware version is too far behind the latest, you will have to go to the Cisco website and download and install any versions in between your current installed firmware version and the latest firmware version.
Much like when you provisioned your phone, you will insert a URL into your web browser that instructs your phone to download and install the latest firmware from our server.
Below is the URL you will need for firmware updates on you Cisco SPA-504.
(NOTE: Please replace the leading x.x.x.x with the LAN IP address of the phone on your network.
To find your phone's LOCAL LAN IP address, consult your router's documentation.
After your firmware updates, your phone should reboot and then you're all set.