no, they have simply identified someone whom they think has no alternative to just bleeding more. Ah, the perks of the monarchy.
the story i heard was not about usage percentage by time, but rather usage percentage by bandwidth. modems squeeze every possible transition out of the 3KHz band, while voice calls have few tones and much silence. this means a modem call takes more bandwidth out of the inter-CO trunks and LD aggregates. the telco's don't use strict DS0a TDM internally. the only reason why usage percentage by time matters to a telco is to differentiate between the economic impact of G3 FAX vs. V.32bis modems: they both use all of the link's transitions but FAXes are usually short lived and so there's nothing to worry about. i'm not happy about the trend toward detecting modem users and charging more for them, but it's an inevitable technical/economic necessity and that means the PUCs around the united states are all going to have to let it happen. what's amazed me for the last few years is that it's taken the telcos so long to realize what they need to do and do it.