The first thig is to check if the phone is registering with Voxalot.
You can check by Logging In to your Voxalot account page. Then go to Account Summary, scroll to the bottom of the page, and click on Device Registrations.
http://www.voxalot.com/action/deviceRegistrations
Check if the echo test works (600) and other test calls (Eg *266300)
The next step is to try and establish a call to the phone from another Voip account outside your network or through a SIP Broker access number.
The phone might not be reachable at all or you might be able to reach it but not be able to establish 2-way communications, or it might just work perfectly.
I aso suggest that you set Voice Mail active to No while you are doing these tests as the ringing you might be hearing is just the system waiting for the Voice mail responses to activate.