All of this info was found on a forum post on the Cisco website and I have tested and verified it works.
To backup your Cisco SPA 50x Series IP Phone’s config, in your web browser, enter the URL of your device’s web management page followed by “/admin/spacfg.xml”.
http://192.168.0.1/admin/spacfg.xml
In the web browser, go to File > Save As and rename the file ending in “.cfg”
spa.cfg
To restore the config on a different device, bare minimum, you will either need to change the MAC Address and Serial Number in the xml file or you might be able to just leave those fields blank (that I haven’t tested). Also, the phones should be running the same firmware version. Last but not least, you will need to be running a TFTP server to grab the config file from. Here is an example of how to resync the profile from a TFTP Server with an IP Address of 192.168.0.225:
http://192.168.0.1/admin/resync?tftp://192.168.0.225/spa.cfg
Once you do this, the phone should reboot and you should be on your way.