The main task was to open tcp and udp (specific Voice IP provider settings) in OpenSuse 11.0 server firewall.
To do that, open in terminal as "root"
Then go to Security and Users->Firewall
Switch to Expert Mode and go to Custom Rules.
Click "Add" buton and input the needed settings:
Source Network: 0/0 (this mean from all IP)
Protocol: Tcp or Udp
Destination Port: xx...
Source Port: xx...
Go to "Start-up" and click "Save Settings and Restart Firewall Now"
That's all, enjoy :)