What Does Numbering Plan Mean?
A numbering plan is a telecommunication scheme through which telephone numbers are assigned to subscribers and telephony endpoints. Each telephone number is an address assigned to an endpoint in a network through which a designated subscriber can be reached. Depending on the local telephony requirements and network, a numbering plan can follow a number of strategies.
A numbering plan is also known as a telephone numbering plan.
Techopedia Explains Numbering Plan
A numbering plan can be generally divided into open and closes numbering plans. An open numbering plan can assign various numbers of digits, while a closed numbering plan has a set number of digits. Numbering plans, in many cases, most significantly depend on the geographical zone of the subscriber: a fixed number of area codes is allotted depending on the state, city or region. Any user dialing from within a network must first specify the area code if dialing outside their local zone. Not only public switched telephone networks (PSTNs) but private telephone networks employ numbering plan schemes as well.