You can still find archival versions of the Facebook Chat 1.0 JAR on legacy mobile sites like Mobiles24 or PHONEKY .
Unlike the static mobile web, the app allowed users to set their status (Available, Busy, Invisible). It showed which friends were online in real-time, a feature that was surprisingly difficult to track on the standard mobile web version of Facebook at the time. facebook chat by msonar for java phones
While the app no longer works with Facebook, you can find .jar files on old software archives like Dedomil.net or Mobile9 for emulation purposes (e.g., using J2ME Loader on Android). Do not expect login functionality. You can still find archival versions of the Facebook Chat 1
You can still run Msonar’s app today, though Facebook has deprecated the old XMPP chat service. Here’s how to experience it: facebook chat by msonar for java phones