According to this news story on ISPreview.co.uk, BT Retail are quietly trialling Carrier Grade NAT on some of their customer connections,  This is the first of the ‘Big 5’ that are known to be doing so, not long after the Plusnet (also owned by BT) trial took place.  To me, this suggests that we are now at the point where even the big ISPs no longer have the IPv4 addresses to allocate to customers, and the article suggests that up nine other customers will be sharing a single address, if you have been placed on this trial.

The worry here is that all of the Big 5 will just use this as an excuse to delay IPv6 adoption further, when what we really need is mass adoption of IPv6 folllowed by, if and only if necessary, CGNAT for all the “legacy” applications still left on the Internet.

BT’s official FAQ on the matter can be found here.