10-08-2011, 04:04 PM
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I. Introduction
In the context of traditional circuit-switched telecommunications networks, number portability is the ability of end-users to
retain their telephone numbers when changing service providers, service types or locations. It is believed that when fully
and nationally implemented by both wireline and wireless service providers, number portability will remove one of the
most significant switching costs for consumers and will encourage competition in the telecommunications industry.
With the Telecommunications Act of 1996, Congress addressed the issue of number portability by formally defining it,
setting deadlines for implementation, and requiring all carriers to deploy it. To ensure standardization across platforms for
all participants, the Federal Communication Commission (FCC) instructed the North American Numbering Council (NANC)
to determine which number portability method to employ. The location routing number (LRN) method proved to be the
most efficient among alternatives and is the method now widely implemented in wireline environment. The sections
below discuss in detail number portability and LRN architectures.
II. Types of Number Portability
There are three types of number portability:
1) Service provider portability.
2) Location portability
3) Service portability
Service Provider Portability
Historically, all directory numbers in a given Numbering Plan Area - Central Office Code (NPA-NXX) were assigned to a
single telephone switch. By owning their customers' numbers incumbent local exchange carriers (ILEC) had significant
advantages over competitors. When customers wanted to switch service, they had to give up their number which imposed
on them inconvenience/switching costs. With the Telecommunications Act of 1996, FCC mandated that all numbers be
portable to all local exchange competitors (ILECs, CLECs, cellular, etc.). The Act defined service number portability as the
ability of end users to retain existing directory numbers (DN) at the same location as they change from one service
provider to another.
The introduction of service provider portability allows individual DNs in one NPA-NXX to be moved to a different switch. To
ensure that calls are routable to a portable number, FCC approved the concept of location routing number. Under the
number portability standard, each switch that hosts portable number is assigned a 10-digit LRN that is used to route calls
to that switch. All LNP-capable network elements have to maintain a list of NPA-NXXs that are considered portable. That
particular FCC mandate only refers to porting numbers within a given "portability domain" or rate center.
Location Portability
Location portability is the ability of users to retain existing DNs without impairment of quality, reliability, or convenience
when moving from one physical location to another. Location portability allows a given telephone number to be
associated with any network termination device, independent of location. It also allows customers to take their DNs when
they move to another geographic location outside of the original rate center. Although FCC does not address location
portability at this time, it leaves room for changes in the future.
Service Portability
Service portability is the ability of users to retain existing DNs without impairment of quality, reliability, or convenience
when switching from one service to another provided by the same telecommunications carrier. FCC is not addressing
service portability at this time and requirements for service portability are still undefined.
I. Introduction
In the context of traditional circuit-switched telecommunications networks, number portability is the ability of end-users to
retain their telephone numbers when changing service providers, service types or locations. It is believed that when fully
and nationally implemented by both wireline and wireless service providers, number portability will remove one of the
most significant switching costs for consumers and will encourage competition in the telecommunications industry.
With the Telecommunications Act of 1996, Congress addressed the issue of number portability by formally defining it,
setting deadlines for implementation, and requiring all carriers to deploy it. To ensure standardization across platforms for
all participants, the Federal Communication Commission (FCC) instructed the North American Numbering Council (NANC)
to determine which number portability method to employ. The location routing number (LRN) method proved to be the
most efficient among alternatives and is the method now widely implemented in wireline environment. The sections
below discuss in detail number portability and LRN architectures.
II. Types of Number Portability
There are three types of number portability:
1) Service provider portability.
2) Location portability
3) Service portability
Service Provider Portability
Historically, all directory numbers in a given Numbering Plan Area - Central Office Code (NPA-NXX) were assigned to a
single telephone switch. By owning their customers' numbers incumbent local exchange carriers (ILEC) had significant
advantages over competitors. When customers wanted to switch service, they had to give up their number which imposed
on them inconvenience/switching costs. With the Telecommunications Act of 1996, FCC mandated that all numbers be
portable to all local exchange competitors (ILECs, CLECs, cellular, etc.). The Act defined service number portability as the
ability of end users to retain existing directory numbers (DN) at the same location as they change from one service
provider to another.
The introduction of service provider portability allows individual DNs in one NPA-NXX to be moved to a different switch. To
ensure that calls are routable to a portable number, FCC approved the concept of location routing number. Under the
number portability standard, each switch that hosts portable number is assigned a 10-digit LRN that is used to route calls
to that switch. All LNP-capable network elements have to maintain a list of NPA-NXXs that are considered portable. That
particular FCC mandate only refers to porting numbers within a given "portability domain" or rate center.
Location Portability
Location portability is the ability of users to retain existing DNs without impairment of quality, reliability, or convenience
when moving from one physical location to another. Location portability allows a given telephone number to be
associated with any network termination device, independent of location. It also allows customers to take their DNs when
they move to another geographic location outside of the original rate center. Although FCC does not address location
portability at this time, it leaves room for changes in the future.
Service Portability
Service portability is the ability of users to retain existing DNs without impairment of quality, reliability, or convenience
when switching from one service to another provided by the same telecommunications carrier. FCC is not addressing
service portability at this time and requirements for service portability are still undefined.
