When using nmap and autoscan on my wifi network I can see all regular devices connected to it - the router, laptops and even the N810 (that btw for some reason calls the network card 'Danmark A/S' ).
But..if my girlfriend connects her iPhone to the wifi network it doesn't seem to get an IP address assigned to it in the 192.168.1.x-range.

After she connected we went to whatsmyip.org on her phone and it gave an IP address of 71.202.something.something.
First I thought that maybe it was a static IP address and did an nmap scan of the exact address and it found it.
It also mentioned comcast - which is the internet service I use.

Later on she left and I for some reason did the same nmap scan of it - and nmap said it was still 'active'.

Could it be that the 71-address that it showed on her iPhone was not tied to her phone per se - but rather the router (which means I still got no idea what the phone's IP address is)?

I also can't figure out why her iPhone can connect to my router - without getting an IP address in the range it uses.
How can I ever scan my network for any devices connected to it if they can be connected using an IP address outside of the expected range?
Normally I just do for instance an nmap -sP 192.168.1.0/24 scan - can I throw the net wider?

(And yes; of course I know about WEP/WAP, so please if you reply do focus on the above).