Hi all, quick question, been wondering about this for a while and now I gotta know

I know that some members have been banned by various means etc etc, IP addy being one, but how do you know if someone logs in from a mobile device, what I mean is, does a mobile / pda / or whatever give an IP address and if so, is it the same IP, when I'm on my travels and log in from my xda, does it show as being logged in from a mobile and if so is it the same one each time.
Just curious

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Hope you can make out what I mean, I just re-read it and my heads spinning ..lol