Numbering Plan Overview
A numbering plan describes the endpoint addressing scheme used in a VoIP network and
is analogous to the IP addressing scheme used in an IP network. A numbering plan identifies
each VoIP endpoint and application in the network with a unique telephone number.
A well-designed numbering plan should evaluate both current requirements and potential
growth requirements to avoid the need to renumber as more users connect to the voice
network.
Implementing a VoIP network involves designing a numbering plan for all endpoints or
reviewing an existing numbering plan for scalability and completeness. A dial plan can be
designed only after the numbering plan has been completed and after call patterns and
connectivity to the PSTN are understood. All implementations of VoIP require both a
numbering plan and a dial plan.