CounterPath stopped selling Bria 4 in June this year, since then its been Bria 5 which IS supported on High Sierra. They also have an upgrade program for Bria 4

CounterPath stopped selling Bria 4 in June this year, since then its been Bria 5 which IS supported on High Sierra. They also have an upgrade program for Bria 4 depending on when you purchased, with free upgrades if you purchased within 60 days of the Bria 5 launch, and 30% off for anything prior. https://support.counterpath.com/knowledge-base/article/%E2%80%8Bbria-5-retail-store-upgrade-program https://support.counterpath.com/knowledge-base/article/%E2%8... I did my homework, yes I missed out on the free upgrade, but 30% discount ain't bad and with the frequency that they upgrade their softphone versions I think its way more fair than Parallels or other software where you pay $50 every year with very few updates in between.