This standard establishes telephone audio performance requirements, measurement methods, and test procedures for telephones with high receive gain and control of the receive frequency spectrum. This standard addresses audio performance in narrow band telephony frequencies using scientific methods and techniques derived or adapted from current telephone measurement standards. Narrow band is defined as the frequency range between 300 and 3400 Hz.

The current revision of this document addresses analog interface telephones designed for connection to the PSTN (Public Switched Telephone Network). PSTN connected telephones have a narrow band frequency range. Future revisions of this standard may address VoIP and other digital interface telephones including wide band telephones.

The current revision of this document addresses telephones with a handset. Future revisions of this standard may address other telephone device types.