scope:

This standard establishes coding and modulation requirements for 2,400 bit/s modems owned or leased by the Federal government for use over analog transmission channels other than those derived from high-frequency radio facilities. It is based upon techniques described in CCITT Recommendations V.22 bis, V.26, and V.26 bis.

This standard is to facilitate interoperability between telecommunication facilities and systems of the Federal government.

This standard shall be used by all Federal agencies in the design and procurement of 2,400 bit/s modems for use with switched or dedicated nominal 4 kHz channels with the following exception. Secure (i.e. encrypted) voice terminals conforming to North Atlantic Treaty Organization (NATO) Standardization Agreement 4291 may deviate from the requirements of this standard.