TIA ANSI/TIA-470.122 PDF

This standard provides acoustic transmission performance requirements for speakerphone equipped analog telephones intended for connection to terminal adapters and voice gateways that provide wideband speech using packet-based services such as Voice over Internet Protocol (VoIP). These services are often referred to as high definition or HD voice services. The specification range for this standard is 100 to 8000 Hz, but for practical reasons the actual audio bandwidth of covered devices is typically about 150 to 6800 Hz.

This standard is limited to single housing speakerphones intended for use on a desk or table by a single user at a distance of one half meter or closer.

The terminal adapters and voice gateways used to provide HD voice services normally present 600 ohm impedances and are connected to the wideband telephone with very short lengths of cabling. If the wideband telephone is likely to be used in applications where it may also be connected to narrowband voice services, such as the public switched telephone network (PSTN), that provide 900 ohm impedances and may use significant lengths of loop (cabling), then evaluation for compliance with the latest version of the ANSI/TIA-470.120 standard for narrowband analog telephones with speakerphones is suggested.