Yes, communication is encrypted. Just change http:// to https:// in your URL. When logging in thru pbxes.com you get redirected to the right https:// page automatically.
Because there is no domain name for dedicated IPs, and therefore no trusted certificate you will get a warning message to accept the certificate. If you click on "show certificate" within the browser warning, you can see the certificate is for www1.pbxes.com.
From there click "accept risk and continue" to confirm the security exception.