In article , TELECOM Digest Editor noted in response to an article by w_warren firstname.lastname@example.org:
it is still relatively rare. PAT]
The V&H coordinates of the Rate Center associated with a given exchange
> show the physical location to which all calls made to that exchange are
> billed. Although long distance competition has reduced rates and
> sometimes caused competitors to offer flat rate service for long
> distance, each call is still accounted for in the old way, i.e., it is
> recorded as originating in one Rate Center and terminating in another.
> And, please remember that Local Number Portability does _not_refer to
> geographic movement! The "portability" is between competing ILEC and
> CLEC companies which offer service to the Rate Center represented by
> the NPA/NXX code, _NOT_ between Rate Centers! You may change providers
> (e.g., Verizon to Comcast), but the number you port is _still_ "homed"
> on its old Rate Center.
> Cellular users must pay forwarding charges for calls outside their
> Rate Center: their carrier may choose to bundle those charges in with
> their basic service or make any number of other price concessions, but
> the number _always_ stays at its associated Rate Center. That means
> that no matter where the cellular user is located, calls made to
> his/her cell phone _always_ go to the terminating Rate Center first,
> and are then forwarded within the cellular provider's network to a
> cell tower that serves the user's current geographic location.
> As far as the originating office is aware, the call stopped at the
> terminating Rate Center, and it is recorded that way.
Except where VoIP is involved. For example, I could take my VoIP router anywhere there's broadband and keep the same exact phone number.
Even E-911 can be changed on the fly. I'd imagine you'd get some questions from the PSAP when your NPA-NXX doesn't match their area, but the call would still go through.