[Thank You Rush]

I don’t understand the article but I understand your post.. Common sense.

“”You can’t go by area code alone if that what was used.””

[monkeyshine]

It’s the IP address of the device, not the area code.
It doesn’t identify the person, just the device and the location where it was originally set up.
Anyway if you see the same IP address at multiple locations, you pretty much know it’s the same person. People don’t lend their phones to other people very often.