This standard covers the transmission requirements for VGs. For the purposes of this standard, a VG is considered to be a device that performs voice routing functions between:

•Telephones;

•Public and private networks;

•Packet-based networks¹.

VGs include, but are not limited to:

•Packet-based Enterprise equipment that is functionally equivalent to a TDM-based PBX;

•Residential Gateways;

•Voice-over-ADSL Integrated Access Device (IAD);

•Voice-over-Cable Multimedia Terminal Adaptor (MTA).

Telephones referred to in this standard are assumed to comply with the requirements specified in:

•ANSI/TIA-470.110-C for analog telephones, or

•ANSI/TIA-810-B for digital telephones.

¹ For historical reasons, the terms "IP" and "IP-based networks" are used extensively in this standard in a generic fashion, but the more generic terms "packet" and "packet-based networks" are now more appropriate. While it is not practical to replace every instance of "IP" with "packet" in this standard, it is the intent of this standard that "IP" and "packet" have the same generic meaning.