Using Kismet to get IP Range

Hey I am a little confused. I cannot seem to get kismet to give me the ip address range of any wireless network. I have plenty right here and none of them give out range. Most are using wep( dont know if this matters much).
Can anyone tell me either how to use kismet to pick of the ip range from the packets or some other way of picking it up?

The reason I am asking is because if a router hasn't been configured to offer an IP through dhcp then you cannot become part of the network unless you know the range and assign one statically right?

Thanks in advance for help :happy:

Intro to Kismet:

http://www.linux.com/feature/139754