Neat! I didn't know how that worked. The little ISP I used to do some things for had physical POPs in different cities and AFAIK never went with Megapop or similar. Eventually, their POPs became all-in-one card cage devices that took a combination of PRI and T1 circuits and screwed them together with PPP, which seemed quite highly integrated to me at that time.

It does look like these may be Starnet/Megapop numbers, based on the panix.motd.megapop newsgroup mentioned on Panix's website. I did spend a minute trying to find who (if anyone) is steering the remaining dregs of Megapop, but I didn't make it very far.