America OnLine split off some of its European operations a few years back and like you say sold off the UK broadband side to CPW and thats now a separate entity.
America OnLine (Corp) is still very much alive and kicking and has their fingers in more pies than is first apparent. At one point in the early 2000's I thought they were about to take over the net as they seemed to be buying just about anything that was going.
I think google beat them to it though
AOL corp is huge.. they own several large marketing companies that serve internet ads, and as mentioned they did go through a spell of taking over good internet apps.
ICQ was brilliant and way ahead of MSN - IMHO it was one of the best chat clients ever- - until aol got its mitts on it.
I used to be a big netscape fan until AOL killed it with bulk and practically made it unusable.. the only good thing that came out of that was Mozilla.
As well as marketing ads both worldwide in th UK AOL corp own things like some of the popular messengers such as AIM or ICQ. They own Netscape, Bebo, MapQuest and many many more internet apps... just do a search on "AOL buys".
However back to port 5190, its most likely to be an Instant Messenger application such as AIM, ICQ, Trillion etc.
Mike may not even be aware that he has AIM on his PC.. I recall installing something fairly recently that would have installed AIM automatically if I hadnt read the small print properly first.
