Thanks for triggering the ole brain cells boatman!
The solution is to add the port number to the proxy address. So in the instructions for Configuring your X-Lite Softphone to Use Voxalot, Step 4 should say:
- Address: us.voxalot.com:5060
This fixes X-Lite to be able to call voicemail and echo test (*500 & *600.)
- Stoker