> like pretty much every cell carrier

TMo US gives me a whole routed /64. Why build and staff v6 NAT devices for no reason? At least several years ago several cell carriers were all about v6 to reduce the volume of v4 traffic they carry, because v4 requires expensive addresses, expensive nat boxes, and expensive people to feed and care for the NAT boxes.

Honestly, I don't know why so many carriers do v6 with NAT, cause intuitively they wouldn't. Maybe someone else knows. I know why a home or office would do it, it's easier to reason about there.

Can you give an example of an ISP doing IPv6 NAT?

AT&T

I can't see anything in their documentation about that, or anything on forums/Reddit.

Users ask about prefix delegation and advanced configurations, but all start from being allocated a /64.

I got a private IPv6 only on AT&T cell when I checked a couple of years ago (to be clear, not a public one with inbound-deny). Will check again.

Edit: Ok not sure what to make of this now. On an iPhone rn so it's tricky, the Net Analyzer app says I have 5 2600:s on cell, which should be the public range, but my public IP according to test-ipv6.com is a different 2600: from all the above. Wonder if those 5 are actually the EPC.

There's an HN comment about them using NAT: https://news.ycombinator.com/item?id=23025344 and this forum thread https://wirelessjoint.com/viewtopic.php?p=25357

There's an old Reddit thread where someone said at first there's no NAT, but then realized there is https://www.reddit.com/r/ATT/comments/8k680y/cellular_public...