This is normally a network set up issue or router issue.
1. Are you set up on a dynamic or static IP address? It must be dynamic.
2. Disable SIP ALG on your router settings, please click here to find out more.
3. Enable DHCP on your router
4. Enter a STUN server by entering stun.icomplete.com into the STUN server settings on the Softphone set up.
If you need further assistance with setting up your X-Lite softphone please visit the link below: