At this moment there are 360 servers with 834 players (humans and bots) playing Jedi Outcast.
Make sure you have updated to version 1.04 if it didn't come that way already. Start the multiplayer game, open your console (Shift and ~) and enter "/version" without the quotes. It should say 1.04. If it isn't, download the 1.04 patch from www.lucasfiles.com
If you still can't see any servers, your firewall or router is probably keeping the game from accessing the Internet. Disable your firewall or tell it to let the game communicate with the Internet. You might have to open up ports 28060-28063 and 28070-28081 on your router, if you have one.
And many many players play both Jedi Outcast and Jedi Academy online with dialup. When you can finally see the servers, sort the list by ping from lowest to highest and stick with servers that have a low ping.
By the way, you will find that some servers have weird "rules" such as you can't attack someone who is standing around with their saber turned off. They will "punish" you if you don't comply with their "rules". Those rules are made-up and not official. I avoid servers like that. You will find that Capture the Flag (CTF) and Duel servers are generally free of made-up added-on "rules", although most duelers demand that you make a "bow" movement before you begin