High Quality Content by WIKIPEDIA articles! TIA/EIA-920 is a telecommunications standard from the US Telecommunications Industry Association, a 1988 offshoot of the EIA. The standard establishes wideband audio performance requirements for wireline telephones which transmit their signals digitally. Audio wideband is defined as 150 Hz to 6800 Hz. The technical standard refers to handsets, headsets, and speakerphones. It does not specify digital protocols or encoding formats. Nor does it concern how the transducers are connected to the telephone.