What makes LNP possible? The Location Routing Number

What is number portability?
Number portability is the ability to switch Service Providers while keeping the telephone number.

What makes number portability possible?
Number portability is made possible thanks to the Location Routing Number (LRN).

What is the Location Routing Number (LRN)?
The LRN is a unique 10-digit telephone number that is assigned to each switch.

What does the Location Routing Number (LRN) ensure?
The LRN ensures call routing is done properly through the Public Switched Telephone Network (PSTN).

How was a telephone number's original state, rate center, Service Provider, and carrier type identified before Local Number Portability (LNP)?
Before LNP, a telephone number's original state, rate center, Service Provider, and carrier type were identified by the Number Plan Area (NPA) and the NXX.

What is the Number Plan Area (NPA)?
The NPA is the 3-digit area code of a phone number.

What is the NXX?
The NXX is the 3-digit number which identifies the central office.

Reasons for porting

What are three reasons a telephone number might need to be ported?
Three reasons why a telephone number might need to be ported are:

  1. Inter-carrier or competitive porting - When a telephone number moves from the current Service Provider to a new Service Provider.
  2. Intra-carrier porting - When a telephone number moves from one switch to another within the same telecommunications Service Provider's network.
  3. Number pooling - When a telephone number moves to a new Service Provider in blocks of 1,000 to create an inventory of unassigned telephone numbers.

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Subscription version, explained

What is each telephone number entered into the Number Portability Administration Center (NPAC) known as?
Each telephone number entered into the NPAC is known as a subscription version.

What information does a subscription version of a telephone number in the Number Portability Administration Center (NPAC) contain?
The information a subscription version of a telephone number in the NPAC contains includes:

  • The Service Provider ID (SPID) - The Local Number Portability Administrator (LNPA) assigns this to all approved applicants to the NPAC.
  • Service provider type - Wireless, wireline, or VoIP.
  • LRN.
  • SS7 Destination Point Codes.

What are SS7 Destination Point Codes?
SS7 Destination Point Codes are unique addresses that identify individual network elements for a Signaling Point used in Message Transfer Part (MTP) to identify the destination of a Message Signal Unit (MSU).

What optional information can a subscription version of a telephone number in the Number Portability Administration Center (NPAC) contain?
Optional information a subscription version of a telephone number in the Number Portability Administration Center (NPAC) can contain includes:

  • Service Type Alternative SPID.
  • Billing ID.
  • End user location and type.

Call flow for ported telephone numbers

What is the sequence of events when a ported telephone number is called?
The sequence of events when a ported telephone number is called is:

  1. A call is made to a ported telephone number.
  2. The Initiating Service Provider's switch launches a query to find out if the number has been ported.
  3. If yes, the LRN of the new switch is provided.
  4. If no, the call is routed based on the telephone number.

Steps of the LNP Porting Process

The FCC has mandated simple one-number port requests be completed within ... ... ...
The FCC has mandated simple one-number port requests be completed within one business day.

What are the steps of the Local Number Portability (LNP) porting process?
The steps of the LNP porting process are:

  1. The New Service Provider notifies the Existing Service Provider of the port request.
  2. The Existing Service Provider validates and confirms the subscriber's information.
  3. The New Service Provider lets the NPAC know of the port request.
  4. The NPAC creates a pending port and sends a notification to the Existing Service Provider.
  5. The Existing Service Provider concurs the port and agrees on the port date from the New Service Provider or the Existing Service Provider allows the NPAC timers to expire.
  6. On the agreed upon date/time, the new service provider tells the NPAC to activate the port.
  7. Once a ported number is activated, the information is broadcast from the NPAC to the Local Service Management Systems (LSMS's).