scope:

This standard provides transmission requirements for analog telephones when used with a headset. The requirements in this standard apply to telephones intended to be connected to the Public Switched Telephone Network (PSTN). These requirements should ensure compatibility and satisfactory performance to the user in a high percentage of installations. The interface between the telephone and the headset is outside the scope of this standard.

Several performance measurement procedures are established today, each of which yields standardized measurement data that may be used for the comparison of different products. This document may reference only a single procedure or specific equipment; however the intent is not to be all-inclusive. Any measurement procedure and equipment that can result in an identical measurement is considered valid.