This revision of Recommendation X.440 is a consolidation of Recommendation X.440 (09/92) and Amendment 1 (11/95).

This Recommendation defines an OSI Message Handling System protocol that is intended to be used in the exchange of voice encoded messages in a store and forward manner as specified in Recommendation F.440.

The protocol specified in this Recommendation is based on the ITU-T X.400-series Recommendations and ISO/IEC 10021 Parts 1 to 7.