This standard addresses IP-based digital telephony (sometimes referred to as "Voice over IP") on the VHN. As the VHN is inherently digital it does not address analog telephony; nor does it address non-packet digital telephony, such as the streaming service provided by ISDN. However, future versions of this standard may address non- IP telephony.

Although this Standard has been issued as a separate document, it is an integral part of CEA-851, "VHN Home Network Specification." Requirements and specifications in CEA-851 also implicitly apply to the functions and devices described in this Standard, unless there specifically stated otherwise.

Also, note that this Standard defines the requirements for implementing a telephony function on a VHN. As such, it is not a device description. Any VHN device that implements telephony is also expected to implement all other parts of CEA-851 that are applicable and appropriate for such a device. For example, CEA-851 requires that a VHN device support a web server; thus, any device implementing the telephony function, as described in this Standard, would be expected to include a web server that would conform to the requirements in CEA-851.