A telephone number is a unique numerical identifier assigned to a telephone line or device for making and receiving telephone calls. Components of a number are central office code, country code, area code, and rate center.

Central office code, country code, area code, and rate center

• Central office code - The central office code, also known as an exchange code. It identifies a telephone exchange within a particular area code and helps to route calls within the local telephone network. See Create a central office code to learn more.
• Country code - A country code is also referred to as an international dialing code. It’s generally a one to three-digit code that is dialed before the area code and telephone number when contacting to another country. See Create a country code to learn more.
• Area code - An area code is a number used to identify a geographic region within a country. See Create an area code to learn more.
• Rate center - A rate center is a geographic area used for determining the rates and billing associated with telephone services. It’s typically defined by a telephone exchange or a cluster of exchanges within a local calling area. Each rate center has its own set of pricing and billing structures for phone calls within that area. See Create a rate center to learn more.

  To learn more about telephone numbers, how to manage and assign them, see Create a telephone infrastructure