That may be true, but the tariffs did not apply to any CPE systems, since the customer owns the equipment and could order any type of service! Although the operating companies may have had other ideas, it was the operating companies that wrote the tariffs. The PUCs never wrote any tariffs.
At one time (1970 - 1980s) "trunks" (TMB/TM2) were cheaper than 1ML/1MB business lines in California Pacific Bell area. Since they were usually designed with a VFR, the transmission level was between -3.0dB and -4.0dB loss, unless you were on a short loop close to the CO. But then that changed and CPE systems became multi-functional rather than just a key system or PBX. Rates had changed and some folks did not want to pay for trunks. The other part had to do with the FCC registration code of the system or hardware.
Some of the BOCs were easier to deal with than others. Really all you had to do is give them the "right" registration code when ordering service. But that is very moot these days. But some of the effects linger.
It is interesting, now that I think about it that the AT&T/LUCENT/AVAYA stuff is the only manufacturer that did anything like this on a system. Does anyone know of any others that did this?
....JIM....