[VoiceOps] Preventing calls to cell phones with guaranteed accuracy

[Paul Timmins]

> On Aug 25, 2015, at 23:49, John Levine <johnl at taugh.com> wrote:
> 
>>> most landline carriers won't port it to a landline if it's out of
>>> ratecenter.
>> 
>> I thought ports were only possible within a rate centre, and so by 
>> definition impossible to port to a carrier which doesn't operate in that 
>> rate centre?
> 
> It is my impression that ports are technically possible anywhere
> within a LATA, but for business reasons most telcos won't port between
> rate centers.
> 
> They're definitely not possible across the country because long
> distance calls only do the LNP lookup after routing the call to
> the destination tandem.  (That's the "L" in LNP.)

Your impression is correct. My commentary regarding cross-national number access on a POTS line was based on the idea i'd be trucking it across my network from a tandem in California in that example across my network to detroit, and dropping it on your doorstep, but yes, LATA. And the business reason has to do with local calling areas if you're not on an unlimited plan, as well as intercarrier compensation even if you are.

-Paul