Get the latest version of Landline for Windows.
At this time, Landline is known to cause false positives by Windows Defender. This is due to the unsigned nature of the application. I simply don't have $400 to spend on getting an application 'signed' by an insignificant third party. However, each release's VirusTotal results can be viewed here.
Only the following facilities are configured for Landline at this time:
If your ARTCC is not listed and you'd like access, have your facility administration contact Ethan Martin via Discord.