Attachments to the Public Switched Telephone Network (PSTN) Category II Attachment Requirements for 300 Bits per Second Duplex Modems Standardized for Use on the PSTN (the Text of This ETS May Be Utilized@ Wholly or in Part@ for the Establishment of NET 2
"This ETS specifies the technical characteristics to be offered by modems seeking Category II approval for duplex operation over the PSTN at 300 bits per second. The modulation scheme specified is that described in CCITT Recommendation V.21 [4]. The term ""modem"" in the context of this ETS includes all physical implementation practices for voice band modems which are galvanically connected to the PSTN. This ETS specifies two modes of operation: answer mode and call mode. NOTE: Modems can provide either simply one of the above modes or provide both modes together with facilities for selecting either of the two modes. This ETS also contains descriptions of the tests to be performed in order to confirm compliance with the functional requirements contained herein. A general description of the test conditions and test requirements is given in Annex A (Normative)."