New York, NY
reply to josephf
Don't forget that telephone is something "invented" over 130 years ago which has barely changed from its original basic "principles" during this time.
An SS7 (signaling system v.7) had been widely deployed in mid of 60's and has not changed since that either.
Moreover - a "modern" IP communication technology was also developed [by DARPA, as an aftermath of Caribbean crisis, in order to overcome possible civilization's dusk due to complete disconnection among remaining after nuclear war "islands of surviving life"] in mid of same 60's. It was greatly extended and expanded since then, but basic principles are still the same.
I'm saying this about "IP" because it works, in means of routing, much the same way as SS7. Any IP address belongs to its own, so called "portable range" sub-network. Those sub-networks are allocated and assigned to ISPs by very few global entities called Internet Numbering Regiostries - for example the one in America is called ARIN - American Registry of Internet Numbers. Another one - in Europe is called RIPE, and so on. When a portable network is assigned to an ISP - that ISP may begin announcing it via BGP4 to different Internet backbones who "spread" that information to all other interconnected IPSs and independent BGP4 peers. Then much smaller ranges, down to former Class-4 (256 addresses) or even smaller - down to a single IP address - are being assigned to ISP's customers, equipment or colocation. An ISP's customer may in turn be "multihomed" - connected to more than one ISP - then such a customer requests from its "main" (called "homing") ISP a permission to re-announce their IP allocation to its other peers (homes) - this way a network becomes "ported" to several other ISPs. I'm not going into details of this mechanism, but want to say that should a "main" ISP's router fail - all other "homes" will be screwed as well...
Even much more than one can imagine. As a matter of fact - due to "softened", "loosened" and "relaxed" regulations (or complete lack of such) for IP world - some huge IP routing disasters happen almost each year, sometimes - more than once a year. Because some ISP may mismanage their BGP4 router or routers (called Autonomous System) to begin announcing NOT their IP networks or IP ranges _wider_ than their own - to their BGP peers. Then results are unpredictable causing sometimes whole countries and continents to lose their Internet connectivity partially or completely. There are some "techno-ethical" behavioral rules for network managers as well as "techno-survivor's" rules for BGP backbone network managers, but smaller and larger IP-world-tragedies keep happening.
On an opposite side- there are virtually NO such tragedies in the telecom world. That's right - for a short time one may cause a "small" sabotage or mishandling, but that would be a last time he/she could do it. The rules of conduct are very strict in the telecom for xLECs; it's a matter of survival for a LEC - to control and prohibit any possible network management practices leading to TDM inter-network problems.
There are many books written about how telecom works - you're welcome to get your knowledge from them.
number pooling? Do you have number pooling in New York? I know we do in California in most (or all?) area codes.
With number pooling, is there still the primary owner of the NPA-NXX, which would be distinct from the individual owners of the NPA-NXX-X? Would it at all make it easier to have the ported number work, should individual owners of individual 1k (or fewer?) blocks be completely down?