WorldClient and Cisco PIX firewall conflict
There may be a conflict between older versions of WorldClient and Cisco PIX firewalls.
Older versions of WorldClient used port 2000 by default. This may cause a conflict if you are behind a Cisco PIX firewall.
The Cisco PIX firewall uses port 2000 for Voice over IP traffic. The “skinny” fixup below is used to facilitate VoIP traffic and is what may interfere with WorldClient.
If you are using Cisco Secure PIX series firewall, the protocol for VoIP (called Skinny Protocol in the Cisco Secure PIX series) uses 2000 port.
To resolve this problem, you should change the configuation of FIXUP protocol as the following. 'fixup protocol skinny 2000 ==> no fixup protocol skinny 2000'