This standard establishes voice performance requirements for narrowband digital telephones and devices. Transmission may be over any digital interface including wired, or wireless, 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, PBXs, or personal computer-based telephones. Examples include: ISDN telephones, digital proprietary telephones, VoIP telephones (corded and cordless), softphones (such as laptop computers), IEEE 802.11 telephones, USB telephones, USB devices, DECT telephones, Bluetooth® Telephones and Bluetooth devices.

In principle, this document can be used to evaluate wireless devices and other devices where the Alaw and mu-law codecs are not supported for the full audio channel. In this case the targets specified in this standard may not apply. If A-law or mu-law codecs are supported they shall be used for testing to compliance to this standard.

For telephone systems that incorporate a Universal Serial Bus (USB) type interface or a Bluetooth type interface to a host (such as laptop computers), it may be desirable for the USB or Bluetooth device to meet the requirements of relevant clauses of this standard, where the host device is assumed to have a 0 dB loss plan, in its default state. It may be desirable for the device to provide gain adjustment for both the send and receive channels. When connected to a host device, the full system shall then meet all of the associated requirements of this standard. A USB or Bluetooth device may have a handset, headset or speakerphone configuration.

Technical requirements are specified for handset, headset and handsfree (speakerphone) modes of operation regardless of the technology used to couple the handset or headset to the telephone.

The test measurement methods in this standard reference procedures in IEEE Std 269 and IEEE Std 1329 where applicable, as well as the appropriate ITU-T Recommendations. Several performance measurement procedures are established which can 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 all-inclusive. Any measurement procedure and equipment that can provide adequate results within the accuracy of the original 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.