On this page you can find an template example that contains >90% of the used parameters.
<?xml version="1.0" encoding="utf-8"?>
<settings>
<phone-settings>
<web_language perm="RW">English</web_language>
<language perm="RW">English</language>
<timezone perm="RW">GER+1</timezone>
<ntp_server perm="RW">pool.ntp.org</ntp_server>
<webserver_type perm="RW">http_https</webserver_type>
<setting_server perm="RW">http://profile.gigaset.net/P820-{mac}.htm</setting_server>
<tone_scheme perm="RW">GER</tone_scheme>
<update_policy perm="RW">auto_update</update_policy>
<http_user perm="RW">admin</http_user>
<http_pass perm="RW">Gigaset123+</http_pass>
<admin_mode_password perm="RW">YourAdminPassword</admin_mode_password>
<admin_mode_password_confirm perm="RW">YourAdminPassword</admin_mode_password_confirm>
</phone-settings>
</settings>