Service providers that NAT their whole network?

[Philip Matthews <matthews () nimcatnetworks com>]

A number of IETF documents(*) state that there are some service providers
that place a NAT box in front of their entire network, so all their
customers get private addresses rather than public address.
It is often stated that these are primarily cable-based providers.

I am trying to get a handle on how common this practice is.
No one that I have asked seems to know any provider that does this,
and a search of a few FAQs plus about an hour of Googling hasn't
turned up anything definite (but maybe I am using the wrong keywords ...).

Can anyone give me some names of providers that do this?

Can anyone point me at any documents that indicate how common
this practice is?

- Philip

(*) Some IETF documents that mention this practice:
    - RFC 3489
    - draft-ietf-sipping-nat-scenarios-00.txt
      (now expired, but available at
      http://www.ietf.org/proceedings/02jul/I-D/draft-ietf-sipping-nat-scenarios-00.txt