This addendum provides changes to TSB-31-D, Telecommunications – Telephone Terminal Equipment – Rationale and Measurement Guidelines for U.S. Network Protection. It supersedes the TSB-31-D-1 addendum to the above document.

Clause 2 of this document provides changes to clause 3, REFERENCES and to sub-clause 5.5, Suggested Equipment List (SEL) of TSB-31-D.

Clause 3 of this document provides completely new text for sub-clause 14.2 of TSB-31-D on test procedures for receive volume control. The new text incorporates the changes to the original text of sub-clause 14.2 that were made by TSB-31-D-1 and adds additional text referencing conversational gain test procedures in accordance with ANSI/TIA-4965.

Clause 4 of this document provides the actual conversational gain test procedures in the form of a new Appendix F to be added to TSB-31-D.

The other clauses and sub-clauses in TSB-31-D are not affected.

For the changes provided in Clause 2, additions to the text are shown underlined and deletions are shown using strikeout. The new text provided for sub-clause 14.2 in Clause 3 is a complete replacement for the existing text. Changes resulting from combining that existing text with the text previously provided in Addendum 1 are not marked. Only the additional changes made by this Addendum are shown using underlining and strikeout. Likewise, the completely new Appendix F text in Clause 4 is not otherwise marked. Words that appear in underlined italics are intended as instructions to the reader.