TIA ANSI/TIA-920.120-B PDF

This standard establishes transmission performance requirements for speakerphone devices that function as narrowband (300 to 3400 Hz) or wideband (100 to 7000 Hz)¹ digital interface communications devices, or both. Transmission may be over any digital interface including Local or Wide Area Networks, Firewire/IEEE Std 1394, Universal Serial Bus (USB), public ISDN or digital over twisted pair wire. This includes TDM-based and packet-based (e.g. VoIP) devices. These devices may be connected through modems, voice gateways, wireless access points, or PBXs, or they may be personal computerbased communications devices. Examples include, but are not limited to: Cordless handsets in speakerphone mode, ISDN telephones, digital proprietary telephones, VoIP telephones (corded and cordless), softphones running on personal computers, IEEE Std 802.11 communications devices, USB communications devices, DECT (CAT-iq) telephones, Bluetooth^® communications devices, and HD (High Definition) voice communications devices.

Some communications systems consist of a host (such as a laptop computer) with an interface for a Universal Serial Bus (USB) or radio-linked device. If the host device is assumed to have a 0 dB loss plan in its default state, then the relevant clauses of this standard are directly applicable to the USB or radiolinked device. If the host system provides gain or loss in the send path, receive path, or both, then the relevant clauses of this standard apply to the composite system.

¹ ITU-T Recommendation P.10/G.100 defines wideband as covering the frequency range from 100 to 7000 Hz. It uses the term normal band instead of narrowband to refer to the frequency range from 300 to 3400 Hz.