Number porting is a service that allows users to switch service provider and keep his existing telephone number.
According to FCC regulations, customers in the U.S. has availability to transfer fixed-line,mobile and toll-free numbers. In Canada, there are some restriction in number portability.
If user remains in the same geographic area, number porting is always available, including porting between wireline, wireless and IP providers. Provider cannot refuse to port user number. In the meantime, providers can charge number porting. Sometimes, when user goes to another geographic area, porting is not possible. Similar, service porting is not always available.
According to FCC rules simple number porting of one line not demanding change or tuning hardware should be made for one business day. In practice, it takes several hours. Porting from wireline to wireless providers sometimes takes several days. Toll-free number porting is more complex and can takes 1-2 weeks.
From technical point of view number portability is based on central database and SS7 signaling. The operator that originate a call checks the database and obtains a call route.
Number porting allows users to change service providers to obtain better service without losing a valuable telephone number.