Try to reinstall the application and go Control Panel > Hardware and Sound > Device Manager and update the sound drivers. Go again to Control Panel > Sound and enable the microphone from the Record tab > Properties option. Also, make sure that your Windows and security program firewall doesn't block the connection.
If it says that it cannot register to SIP server it's because the SIP server is not accessible. The problem is that the website of the application does not exist anymore. This means that the servers are gone for good.
Try to reinstall the application and go Control Panel > Hardware and Sound > Device Manager and update the sound drivers. Go again to Control Panel > Sound and enable the microphone from the Record tab > Properties option. Also, make sure that your Windows and security program firewall doesn't block the connection.
If it says that it cannot register to SIP server it's because the SIP server is not accessible. The problem is that the website of the application does not exist anymore. This means that the servers are gone for good.