This standard addresses Aeronautical Mobile Satellite Services operating in the frequency bands 1.5 and 1.6 GHz. DO-210D updates DO-210C and contains new material regarding Inmarsat Aero H+/I services@ intermediate-gain antenna@ channel descriptions@ related physical layer and management characteristics@ and the 4.8 kbps Advanced Multiband Excitation (AMBE) voice codec. New verification procedures related to priority@ precedence@ and preemption are also included. Revisions relate to the Aero H+/I services@ clarifications of requirements@ and a review of verification procedures with respect to the Inmarsat System Definition Manual as well as ICAO Standards and Recommended Practices. The document includes equipment performance requirements@ recommended bench tests and other performance verification procedures@ and installed equipment tests and operational performance characteristics. DO-210D supersedes June 2014 RTCA List of Available Documents Page 83 of 142 DO-210C and should be useful to designers@ manufacturers@ installers@ and users of the AMSS system and equipment.