KoolAssist

Download, open it, and give the person helping you the ID + password shown.

Windows  ·  ready to go

Download for Windows

macOS

Apple Silicon Intel

Linux

.deb (Debian/Ubuntu) AppImage
Mac & Linux — one-time setup (Settings → Network):
ID Server: support.kooltel.com
Key: qBNjf1MH+Pq51erm5ouZfDWQxJ2cH1SFQT9zY73x0gM=
Relay Server: leave blank. (Windows is already configured — nothing to enter.)

Connects only to Kooltel's own server.