Hello Biggizod
If you have not been able to define the default gateway then this sounds like the root of your networking problem.
The default gateway is defined in Manager under "IP Route".
Set the IP Address and IP Mask to 0.0.0.0
Then add the IP address of the next hop router
Destination is the IP Office interface which is connected to the next hope router
There is a wealth of information in the IP Office KnowledgeBase, found at:
http://marketingtools.avaya.com/knowledgebase
Regards
Steve