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Pioneering internet messenger ICQ shuts after 28 years - CNA
(www.channelnewsasia.com)
This is a most excellent place for technology news and articles.
Maybe I'm off by a bit then. I could have sworn I had one in like the 500k range but it must have been around '97 or '98.
I got on ICQ in 97 or 98 to keep up with friends from a MUD and mine was 7 digits. I haven't logged into it in over a decade because when I went back to see if anyone from the old game was around none ever showed up online.