For Polycom Soundpoint IP
Press "Menu" on your Polycom phone. Then choose "Settings", and "Advanced". Enter your password; the default password is '456'. Hit the "Enter" soft key when done.
Next, select "Admin Settings", followed by "Network Configuration".
Scroll down using the arrow hard keys until you see "Server Menu". Select it using the checkmark hard key on your phone.
Server menu
In the "Server Menu", change "Server Type" to HTTP by using the arrow hard keys and Server Address to "e.pbx.io/cfg"
Finally, press the left arrow twice until you see "Save Configuration and Reboot". The reboot process may take upwards of 30-minutes on older phones if a firmware upgrade is required.