I just wonder if i call a entity bean in a session been,

is there any network activities ?

Of course there will B network activity,but it all depends where are UR beans are residing
I meant whethere in the same container ,same machine .
or in the remote place.
So if U R going for frequent calls 2 database then ,use it by wrapping the logic in sesssion beans.
N if less calls are made then directly can call the entity bean.
So it all depends upon your application,how it works and what you need.