Anatomy of a Phone Number Throughout This Guide You'll See Various Cryptic References to Phone Number Components—Cryptic, That Is, Until You Review This Section

Anatomy of a Phone Number Throughout this guide you'll see various cryptic references to phone number components—cryptic, that is, until you review this section. NANP Once upon a time, back when the phone company was all one piece (i.e., pre-divestiture), a plan was established for identifying phone subscribers throughout North America. Known as the North American Numbering Plan, or NANP, the plan specified three components of a subscriber's phone number: a three- digit area code (also called a Numbering Plan Area, or NPA), a three-digit exchange or central office code, and a four-digit subscriber code. 714-893-7725

Area Exchange Subscriber Code Code Code

Other countries have much more complicated numbering schemes. Some countries, for example, use area codes that exceed the length of the subscriber code. Other countries have no consistency in the length of phone numbers—some are 9-digit, some 12-digit, etc. All these varying number lengths may be within 100 miles of each other.

The NANP specified further that the middle digit of an area code must be either 0 or 1, and that the middle digit of an exchange code could not be 0 or 1. This allowed telecommunications equipment to differentiate between the two. In other words, when the second digit dialed was either a 0 or 1, the system knew that the call was long distance, and that the first three digits formed an area code. This method of identifying exchanges (central offices) is referred to as “NNX,” where “N” is any digit from 2 to 9, and “X” is any digit. Eventually it became clear that the number of possible exchange codes using this scheme was inadequate. To rectify the problem, the requirement that the exchange code's middle digit not be 0 or 1 was rescinded (see Ambiguous NPA below). This modified way of identifying exchanges is referred to as “NXX,” where N is any number from 2 to 9, and X is any digit. This change to the North American Numbering Plan made available a considerable number of additional exchange codes, but also made exchange codes look just like area codes, eliminating a phone system's ability to distinguish between the two. Bellcore addressed this problem by recommending that a 1 be dialed for all long-distance calls. Whenever the first digit dialed was a 1, the system knew it was dealing with a long-distance call. “Ambiguous NPA” In the early ‘90s Bellcore determined that the number of possible area codes—or NPAs—was inadequate. So the NANP was modified once again, this time eliminating the requirement that the middle digit of an area code be 0 or 1. In other words, the NXX numbering scheme—N is any digit from 2 to 9, and X is any digit—was implemented for area codes as well. This change has been referred to as ambiguous NPA because it eliminated the system's ability to identify an area code simply by looking at the middle digit—in effect, making area codes ambiguous. The solution was to require that an area code be dialed for all long-distance calls, even those within the same area code. NOTE: Ambiguous NPA is an informal term used within Sprint. The generally accepted term is Interchangeable NPA. NANP Today NANP is now almost universally referred to as NADP, or North American Dial Plan, and we’ll refer to it that way throughout the remainder of this guide. The current implementation of the North American Dial Plan looks like this: 1-NXX-NXX-XXXX

Long Area Exchange Subscriber Distance Code Code Code Identifier Dial Plans The term dial plan, which appears many times throughout this guide, refers to the rules that govern the digits a customer must dial to reach a given location. Some customers use 7-digit dial plans (usually a 3- digit exchange code and 4-digit subscriber code), some use 10-digit dial plans (custom 3-digit area code, 3-digit exchange code, 4-digit subscriber code), others use different custom dial plans ranging from 4–9 and 11–15 digits. Customers determine what dial plans best meet their needs. “Annie” If you go three days without hearing about “Annie,” you've probably set some sort of record. Rarely do more than a handful of Sprint associates assemble without the term “Annie” coming up. “Annie” is actually ANI, an acronym for Automatic Number Identification. ANI refers to a LEC's ability to recognize the phone number of the station from which a call originates. This phone number is passed along to interexchange carriers (such as Sprint) for billing purposes. ANI also makes possible such services as Caller ID and Automatic Call-Back. Caller ID consists of a device that can display the phone number associated with an incoming call, even before the call is answered. Automatic Call-Back lets a person who received a call automatically connect to the station from the call originated. Caller ID and Automatic Call-Back, both of which require ANI, are relatively new additions to the telecommunications horizon. Both services require that the local and long-distance carriers have ISDN, or Integrated Services Digital Network, which has been widely but not universally implemented. A Quick Review NADP: North American Dial Plan, the method by which phone subscribers are identified in North America. NNX & NXX: The old and new formats of area codes and exchange codes, where N is any digit from 2 to 9, and X is any digit. NPA: Numbering Plan Area, or area code. Ambiguous NPA: An area code that follows the format NXX—termed ambiguous because it eliminates the requirement that the middle digit be 0 or 1, making it look just like an exchange code. (Also called Interchangeable NPA.) Dial Plan: The rules that govern what digits a customer dials to reach a given location. ANI: Automatic Number Identification, a process that allows the phone number associated with the originating station to be captured, for billing and other purposes. LATAs Local telephone networks provide calling within a specific geographic area called a Local Access and Transport Area, or LATA, which is essentially a local calling area. Within the LATA are a number of central offices, each providing local telephone lines to a region within the LATA. Each of the local telephone lines at a business or home is physically connected to a LEC by cable placed in the street, reaching literally every building in the LATA. A switch at the LEC's central office connects calls between its local telephone lines and those provided by another central office over a complex network that interconnects all central offices. Local telephone companies offer several methods of access between the customers in each LATA and long-distance carriers. 1+ or Equal Access: Provided by Feature Group D (FGD) trunks. When this access type is used, the central office automatically provides Sprint's network with the telephone number (ANI) and other call data necessary to complete and bill the call. A user, therefore, only needs to dial 1+ the desired long-distance number. Special Access: A dedicated line from the customer's premises to a long-distance carrier's POP. This physical connection does not connect to the LEC's central office switch, but does pass through the LEC's wire center to reach the customer (see the following illustration). Calling Card: The user can access an interexchange carrier's network using a calling card and an 800 number. Non-Equal Access: The user dials 10333, then 1, followed by the number being called. The LEC routes the call to the Sprint network. This is termed casual calling and the LEC bills the user for this call.

Access Options The term access refers to the means by which customers reach the Sprint network and Sprint reaches its customers. Access is not a Sprint product or service; it is owned, tariffed and controlled by the LEC. In some cities, alternate forms of access are provided by private competitors. Access is either switched or dedicated (see illustration below). Sprint Premiere provides a range of access options of both types: Switched Dedicated Dial 1 DAL: Dedicated Access Line (analog) Cellular DDAL: Digital Dedicated Access Line (SDS only) FONCARD T1 LEC Switched 56 (SDS only) Integrated Access (TAP, ITAP & FANTM) ISDN Basic Rate Interface (BRI) ISDN Primary Rate Interface (PRI) Switched vs. Dedicated Access

Switched Access

VAX 9 0 0 0

d ig i ta l VAX 9000-410 Dedicated Access to Sprint POP

to MCI POP MCI Cable Distrib. Switch to AT&T POP Frame AT&T

Switched Access Local Exchange Carrier's Wire Center

Switched access relies on the LEC to switch the call to the Sprint network (or other carrier designated by the customer). Dedicated access bypasses the LEC's switch, and connects to the Sprint network directly. This also defines the distinction between on-net and off-net. Switched access is considered off-net, while dedicated access is on-net.

Switched Access Switched-access calls travel at least part of their route to the Sprint Point Of Presence (the LEC's connection point to the Sprint network) over lines that are shared. That is, the same circuits carry traffic from other users at other times. With switched access, the customer's call goes first to the LEC, which then routes the call to the Sprint network. Switched Access Options Dial 1: Available for Feature Group D lines in all equal access areas. Cellular: Can be used to originate to and receive calls from Sprint's network. VPN Premiere FONCARD: Can be used to originate calls worldwide. FONCARD calls can be initiated by dialing 10333 0+ (except for VOICEcard calls), or 1-800-877-8000. LEC Switched 56: A non-ISDN service available from the LEC that provides a digital connection for Switched Digital Service (SDS) in increments of 56 Kbps. Interconnection between the customer's LEC and Sprint is on Feature Group D circuits. ISDN Basic Rate Interface (BRI): An ISDN-based service available from some LECs that provides a digital connection for SDS in increments of 56 or 64 Kbps. NOTE: ISDN is described in more detail starting on page Error! Bookmark not defined..

Dedicated Access An important characteristic of dedicated access is that, although the vast majority of it is provided by the LEC, this is not always the case. In some areas of the country, Sprint has evaluated and certified alternate carriers to provide access to the Sprint POP, bypassing the LEC. These so-called bypass providers—AAVs, or alternate access vendors, and CAPs, or competitive access providers—usually are located in large metropolitan areas and connect the customer to Sprint using various means, including fiber-optic cable and digital microwave. Dedicated Access Options DAL: Dedicated Access Line. A single, unswitched, analog1 line from the customer's premises to Sprint's network. DDAL: Digital Dedicated Access Line. A leased-line circuit provisioned from the LEC in increments of 56 or 64 Kbps to provide a dedicated (unswitched), digital circuit from the customer's premises (through the LEC's wire center) directly to the Sprint network. NOTE: The term DAL is often used in place of DDAL. T1: A dedicated connection that transmits information at 1.544 Mbps. A T1 line consists of 24 separate channels, each carrying information at 64 Kbps. Since T1 is a digital connection, the customer has much higher quality transmission, as well as the ability to transmit data up through 56 or 64 Kbps. Although the total cost of a T1 access circuit is high, on a per-circuit basis, T1 access is very low cost. T1 is described in more detail starting on page Error! Bookmark not defined.. Integrated Access: Three options for combining services on a single trunk of a T1 connection—T1 Access Partitioning (TAP), Integrated T1 Access Partitioning (ITAP), and Facility Access Network Termination Management (FANTM). FANTM services are described in more detail starting on page Error! Bookmark not defined..

Call Types A central concept to how calls are controlled in VPN Premiere is the distinction between “on-net” and “off- net.” On-net refers to calls originating or terminating on dedicated-access facilities. Off-net refers to calls originating or terminating on switched-access facilities. Another way to look at it is this: A call is “on-net” when it originates or terminates at a facility connected to Sprint's network via dedicated lines. A call goes “off-net” when it must pass through the switch of a LEC, either at the originating end or the terminating end. A call can originate on-net and terminate off-net, or vice versa. In fact, the two possibilities—on-net vs. off-net—define the four valid VPN call types:  On-net to On-net  On-net to Off-net  Off-net to Off-net  Off-net to On-net Off-net vs. on-net impacts the rates Sprint charges its customers because LECs charge a fee for switching customers on and off thE Sprint network. On-net calls bypass the LEC's switch, as well as the switching fee. (See illustration on page 4.) For more information on how these four types of calls are processed, see page Error! Bookmark not defined.. Dialing Sequence

IDDD or ... 10-digit ...... Optional or Optional Optional Authcode 7-digit Authcode Acctg. Code or Speed number

One or the other, but not both

1 An “unswitched” line bypasses the LEC's switch and instead connects directly to Sprint from the LEC's cable distribution frame. See illustration on page 15.  “Optional” in the previous illustration indicates that the customer—the “owner” of the virtual private network—can elect to activate or not activate the authorization and accounting code features. If either feature is activated, the code is required for the call to be completed.  Authorization codes can be pre- or post-dialed, but not both. Accounting codes can only be post-dialed, and always follow an authorization code if both are used.  10-digit dialing must be used with the Automatic On-net Termination feature to ensure on-net termination.  International Direct Distance Dialing (IDDD) must be used with the Automatic On-net Termination feature to ensure on-net termination. On-net to On-net Calling Calls between a customer's locations via dedicated access (DAL or T1) are similar to private network calls.  Highest quality at the lowest cost—Fixed cost facilities. Higher usage = lower $/call minute.  Three dial plan options— - Customer-defined dialing - Public network, 10-digit dialing with Automatic On-net Termination - International Direct Distance Dialing (IDDD) with International Automatic On-net Termination On-net to Off-net Calling VPN calls originate from dedicated-access locations and terminate to switched-access locations. Calls between a customer's locations or to locations off the customer's network.  Calls terminate in the continental U.S., Alaska, Hawaii, Canada, Puerto Rico, the U.S. Virgin Islands and all international locations served by Sprint.  Three dial plan options: - Customer-defined using Virtual On-net - Public network, 10-digit - International Direct Distance Dialing (IDDD) Off-net to On-net Calling VPN calls originate from switched-access locations and terminate to dedicated-access locations.  Customers in low-volume or remote locations can enjoy the high quality, features, and low cost of VPN.  Three dial plan options: - Customer-defined dialing (7-digit only using 1-700 access; see page Error! Bookmark not defined.) - Public network, 10-digit dialing with Automatic On-net Termination - International Direct Distance Dialing (IDDD) with International Automatic On-net Termination  Off-net to on-net calls may be placed using VPN FONCARD from the 50 United States, Canada and selected foreign countries using Sprint Access. VPN FONCARD supports 10-digit, 7-digit and IDDD dial plans.  Calls can be placed using cellular access. Cellular supports 10-digit IDDD ubiquitously, and in some areas customers can also dial *8 followed by a 7-digit number.  Allows smaller locations to become part of the corporate network. Off-net to Off-net Calling VPN calls originate and terminate at switched-access locations, but are considered part of a customer's VPN arrangement.  Switched access locations can dial 10-digit numbers and receive the low VPN off-to-off rates.  Customers in low-volume or remote locations can enjoy the high quality, features, and low cost of VPN.  Customers' employees can call from any phone in the world using VPN FONCARD access.  Two dial plan options: - Public network, 10-digit - International Direct Distance Dialing (IDDD)  Customers enjoy the convenience of one bill from one vendor: Sprint.