Can't make outbound calls from XLite SIP Phone

I successfully configured a X-Lite softphone on a Windows PC to register with my Asterisk server. I recieves calls via SIP just fine. The problem comes wen trying to make outbound calls. Askterisk shows a message saying somthing like this:

“Trying to bridge channel Zap/4 and channel SIP/john…”

But it never happens. There’s no timeout either, it just never bridges.
Ports 5060 and 8000 are open on the server (Fedora based). What could be the problem?