ICQ 2000b is a Windows application. On Linux you can run it using WINE, a compatibility layer that lets Windows programs run on Linux and macOS.

Step 1 — Install WINE and ICQ 2000b

1. Download ICQ 2000b from archive.org.
2. Install WINE using your distribution's package manager, or follow the official guide at winehq.org.
3. Run the ICQ installer from a terminal:

   wine icq2000b.exe

4. Close the Registration Window. When installation finishes, ICQ opens a registration wizard. Do not complete it. Close the window and continue below.

Step 2 — Configure the Flamenet Server Hostname

WINE has its own virtual Windows Registry. Use wine regedit to edit it.

1. Open a terminal and run:

   wine regedit

2. Navigate to:

   HKEY_CURRENT_USER\Software\Mirabilis\ICQ\DefaultPrefs

3. Double-click Default Server Host. Set Value data to icq.flamenet.io and click OK.
4. (Optional) Double-click Default Server Port. Tick Decimal, set Value data to 5190, and click OK.
5. Close Registry Editor.

Important: Do not set the hostname inside the ICQ registration wizard — a bug prevents settings from being saved if you do.

Step 3 — Sign In for the First Time

1. Launch ICQ with wine icq.exe (or from your application launcher). When the first-time wizard appears, select Existing User.
2. Enter your Flamenet ICQ UIN and password. (Get your UIN on the ICQ Sign-In page if you haven't already.)
3. Click Next through the remaining screens until the wizard finishes.

ICQ will connect to the Flamenet server and display your contact list.