Two possibilities:
1) They don't want to talk to you. Rejecting your packets
2) Their return packets are being bounced by your firewall.
If you are using the OpenSuSE firewall, be sure their public IP is allowed explicitly (you can test by temporarily turning OFF the firewall, of course).
If you are using a private IP for Vicidial and have a router between Vicidial and the net, that firewall could be rerouting the packets as well. In this situation, unfortunately, you can not turn off the firewall since it is a function of NAT. You can try the DMZ, but that's not the best way. The best way is to get a public IP for the Vicidial server.
Since I know nothing of your network, it would be silly to guess beyond that.
Happy Hunting!
