(a) Purpose. The commission finds that Integrated Services
Digital Network (ISDN) is an alternative to "plain old telephone service."
At this time, ISDN is not a replacement for "plain old telephone service,"
but rather ISDN provides the public switched telephone network with
end-to-end digital connectivity. As such, ISDN should be made available
to customers at a reasonable price, should be as accessible as possible
to customers who want ISDN, should meet minimum standards of quality
and consistency, and should be provided in such a manner that permits
the dominant certificated telecommunications utility (DCTU) a reasonable
opportunity to earn a reasonable return on invested capital. The provisions
of this section are intended to establish the minimum criteria for
the provision of ISDN.