Addresses the technical issues associated with Customer Premise Equipment (CPE) for on-hook signaling, with or without power ringing, which is able to decode data frames packaged in a Single Data Message Format (SDMF), or a Multiple Data Message Format (MDMF). Specifically, establishes formal criteria for Frequency Shift Keying (FSK) signals and protocol capable of being received by such CPE. This standard was first listed for public review in the May 23, 1997 issue of Standards Action. It is being resubmitted now due to substantive changes to the text.