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">NLD+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>
</phone-settings>
</settings>