This standard establishes transmission performance requirements for handset devices that function as a wideband digital wireline telephone. 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) telephones. These telephones may be connected through modems, voice gateways, wireless access points, or PBXs, or they may be personal computer-based telephones. Examples include, but are not limited to: ISDN telephones, digital proprietary telephones, VoIP telephones (corded and cordless), softphones running on personal computers, IEEE Std 802.11 telephones, USB telephony devices, DECT (CAT-iq) telephones, Bluetooth® telephony devices, and HD (High Definition) voice telephony devices.

Some telephone systems consist of a host (such as a laptop computer) with an interface for a Universal Serial Bus (USB) or Bluetooth 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 Bluetooth 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.

The test measurement methods in this standard reference procedures in IEEE Std 269 and ITU-T Recommendations. Several performance measurement procedures are established, each of which yields standardized measurement data that may be used for the determination of compliance with this standard. Although this document may reference specific procedures or test equipment, the intent is not to be allinclusive. Any measurement procedure and equipment that can result in an identical measurement is considered valid.

NOTE: If the main purpose for testing to this standard is comparison testing of different products, rather than compliance testing, then it is important that identical test procedures and equipment be used when testing the different products.

While the procedures may call out specific test points within the requirements, the full range of the requirements take precedence.