Provides transmission recommendations for connections (including ISDN) carried on the public switched telecommunications network (PSTN), between network interfaces (NIs), that are all digital from end office-to-end office (EO-to-EO) with digital or analog access lines from appropriate end-user terminals or interconnecting networks. This standard was first listed in the January 16, 1998 issue of Standards Action. It is being resubmitted due to substantive changes to the text.