View Full Version : registering a phone number

07-05-2004, 10:04 PM
For some reason my thoughts strayed to this today...

How are phone numbers registered and assigned to a particular phone line?

Assume the format for a phone number is the standard USA phone number:

( [3-digit-area code] ) [3-digit-number] - [4-digit-number]

Obviously area codes are assigned by some governing board. But what about the rest of the numbers? It is noticeable that usually there are a certain set of 3-digit-numbers that usually exist in a single area. For example in my area the common 3-digit-numbers are 855, 858, 463, and 550 (858 is pretty new compared to the other three).

Now, obviously different customers use different phone services, therefore there is no way a phone service could decide the 3-digit-numbers that get used in a specific area. That would have to be done by the governing board as well or maybe some contracting company bought a set of numbers and leases them for use in a specific area.

That then leaves the last 4-digit-number of each number.

Now, it is very possible that in these ordinary phone numbers, a governing board could very easily dedicate certain numbers to certain areas and that would be that, but what about certain companies that have numbers like:


And other creative numbers like that. Would those have to be seperately registered and paid for like a webdomain of sorts in order to have a special number like that?

it's weird having stuff like this on your mind....

07-05-2004, 10:09 PM
Some places let you pick your 4 digits (cells especially), and the rest are just assigned randomly, AFAIK. My ex-gf's place and the grocery store a mile or so away have a number that are only 1 off, so it's not a location thing. Also, if you're moving within the same calling area, you can frequently keep the same number.

Companies can usually pay to register whatever 800(or 888 or 866) number that's available.

07-05-2004, 10:21 PM
our major ones over here are 645, 643, 847, and 781. When we went to get our phone # changed they asked if we wanted to keep the same 645, but we couldn't decide on our other 4 digits.

07-05-2004, 10:26 PM
When I got my cell phone, the first 3 digits were chosen automatically, and I was given my choice of the last 4.

07-05-2004, 10:32 PM
Ordinary telephone numbers (aka land lines) are assigned (in the US) as such (sorry for forget exact nonmeclature):

1 - the country code
NPA - this is the area code, assigned by whoever regulates them
NNX - X is any number between 0 and 9, N has some restrictions I can't remember. Each telecomm has a number of these to use. These are also governed as to who gets which ones.
XXXX - the number are assigned by the telecomm. They can be assigned however they choose.

the toll free numbers are governed in a slightly different manner, and the 555 NNX is reserved for special uses (which is why movies use them so much now)

When you place a long distance call its like climbing a ladder. Your immidate switch will look to see if it covers that country code and/or NNX. If it doesn't it bumps it up to a switch that does inter switch trunking. It looks to see if it covers it. If not it bumps it up. Eventually it reaches a pointer where a switch knows what to do with it. Once it reaches that points it gets transfered to the approiate "branch" and it just starts decending.

07-05-2004, 10:42 PM
Waaaaaaay back, the first three digits stood for the part of the city you were in. In fact, when you called the operator, to dial, you would say Lake 4530 (they'd chop off the 'e'). You can hear some of this if you ever listen to old time radio shows. They never ask the operator for a 7 digit number, they ask for an area.

I'm not sure how they are assigned now, but I know there are certain ones that aren't allowed. For example, no one starts with 1 or 0 so those can be used for long distance. 99 is avoided because it's so close to 911, and 555 is only used in TV shows and Movies so some poor sap won't get stuck with the number from a popular movie...imagine the pranks...

07-05-2004, 10:47 PM
> imagine the pranks...

Everytime a not-555 number comes up in popular culture, the poor bastard with that number gets bombarded. I know it happened recently with a couple movies, and I feel genuinely sorry for whoever gets stuck with "867-5309"

07-05-2004, 10:51 PM
Actually 99 is and 9 are not allowed numbers because that is a code sequence. 911 actually points to a regular telephone number (abit one that is secretive and not in the general NNX). From what I was told at one training classes all switches and PBXs are required to handle and route 911 and 9911 to the same location. And IIRC using the City name or area name was because there was no NNX. And there was a time when telephone numbers were only 6 digits. Fairly soon telephone numbers will use a the full 10 unless there is a change in the number of lines per household average.

Ah found the defination:

N Any digit 2 though 9. X is any digit 0 through 9. This is telephony nomenclature, not computer nomenclature. Accept it, whether it's logical or not.

Ok reading some more it appears NNX are now NXX to allow more numbers.

07-05-2004, 10:51 PM
And for those of you who don't know what Govt is talking about, here (http://www.snopes.com/music/songs/8675309.htm).

07-06-2004, 06:13 AM
wow.. the owner can make good money if he makes the number a premium rate number..

07-06-2004, 07:12 AM
Thantos you were saying certain numbers were assigned by the telecomm, but that cant be possible because my family has changed telecomm companies several times (but stayed in the same house), and our number has never changed. We just change the service.

07-06-2004, 07:31 AM
Thantos you were saying certain numbers were assigned by the telecomm, but that cant be possible because my family has changed telecomm companies several times (but stayed in the same house), and our number has never changed. We just change the service.
well thats possible because of govt regulation on monoploy... The customer has the right to retain the number.. how this works is... when the number is dialed the call reaches the original providers swithc and the switch there knows that the number has been transfered to a different provider and transfered to the respective switch..

07-06-2004, 08:18 AM
There is the problem with terms. When I say telecom I mean the people providing the actual service. These days with deregulation you might be billed by company A but in reality company B is providing the service.

07-08-2004, 12:17 PM
My mother works for SWB and she mentioned a federal ruling on monopolies that give service *carriers the absolute right to use serive *providers lines. Not to metion that the entire US is now routed through ESS (Electronic Switch Systems) versus the Analog system back in the day of Cap'n Crunch (don't ask, google). The ESS has serveral adminstrative advantages over the analog b/c you don't have to pull/switch a new ring/tip pair into central in order to change a subscriber line number. However, as more carriers take portions of providers lines to resell the service you have more middle men and price wars and, in general, is not peachy for Ma Bell. In addition, contracts between Ma Bell and the resellers (for liability purposes) restricts access for company B's repair capabilities. In other words, of your line goes down, only a Bell employee can repair them and they really don't care to mess with carrier lines...so you can get screwed over on the whole deal in the end.

07-08-2004, 10:15 PM
Try to find the anarchists' cookbook. It has a nice section on phone numbers. I don't know if any of it is outdated though. It's funny reading the outdated hacking stuff in it.