Solaris

Yes. But just wait a bit. How to do it via system calls? I'm just a newbie in Unix\Linux\Solaris e.t.c. programming. Can anyone help me? I need an advice probably how to do it or may be what API to read... Please, help...

Sorry I'm bit confused what you are asking here?

I am not sure but hopefully this help.
To view your routing:
# netstat -rn

Routing Table: IPv4
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ------ ---------
192.168.79.128 192.168.79.143 U 1 2536 hme0
224.0.0.0 192.168.79.143 U 1 0 hme0
default 192.168.79.129 UG 1 2216
127.0.0.1 127.0.0.1 UH 265784897 lo0
#

To view "system call'"
#netstat -an <=== this will list all ports and their status
Just an additional note, if you're trying to view a specific port
#netstat -an | grep <port number> <=== this is quicker

Since I am not exactly sure of what you're asking, another beauty for Solaris is
#snoop
I would definetly check the man page ont that command.

#snoop -o <filename> -d <interface>
Example:
#snoop -o new -d hme0
Then once you have your data.
#snoop -i new | grep <what you are looking for>

Hope this helps!