actually a static ip address would set you back about �100 a month. most internet users have a dynamic ip address as it is assigned by the isp everytime that you sign on. this means that the isp can have say a million users but only 900,000 ip addresses. they assume that not every member will ever be on at the same time. you do, that is everybody, does, have an external ip address that is not used by your isp which is used by your phone company to address the phone calls to you and not some bald guy from bradford. this is your WAN address as opposed to LAN. i suppose that ebay could use this but they probably just use a cookie or something.
but i digress, all AB members can do is say something naughty and get banned again. this trade off is much easier than setting up the facility to scan the non internet portion of the modems connection line for the static phone ip and ban them like this. i imagine that this would be very difficult to set up. its ok for ebay. they bought skype for 4-6 billion dollars a few months back. im sure theanswerbank couldnt afford that.
anyway, if you want to find out your WAN ip go here
http://www.whatismyip.com