ct@dde.dk (Claus Tondering) (03/03/91)
Could somebody in the US please inform me about the rules for when you have to dial an initial 1 in front of American telephone numbers? I used to think that if you were dialing a local (seven-digit) number you shouldn't start with a 1, whereas if you were dialing an area code, an initial 1 was required. However, during a recent visit to Florida while dialing certain seven-digit numbers, I was informed by a talking machine that I should dial an initial 1. This prompts three questions: 1) Why do you need a 1 in front of certain 7-digit numbers, but not in front of others? 2) If the telephone system is smart enough to inform me that I need to dial an initial 1, why is it not smart enough to connect me even if I haven't dialed the 1? 3) Are the rules the same everywhere in the US? Claus Tondering Dansk Data Elektronik A/S, Herlev, Denmark E-mail: ct@dde.dk [Moderator's Note: In summary, no, the rules are not the same everywhere in the USA. In almost every case you need a '1' before a ten-digit number. In the case of seven-digit numbers it varies according to the numbering scheme used by the local telco. The telcos usually begin using '1' in front of seven digits when their supply of prefixes without a one or a zero as the second digit begins to run short. A one or zero in the second digit of a three digit number here usually indicates an area code instead of a local exchange code. Using '1' first allows an extended set of exchange codes. There are other reasons as well. The reason they are 'smart enough' to catch the error but unwilling to correct it is because it is possible you actually knew what you were doing but misdialed, reaching a combination that normally requires '1' first. Rather than second-guessing what you might have meant, they toss it back to you to do over. PAT]
goudreau@dg-rtp.dg.com (Bob Goudreau) (03/04/91)
> [Moderator's Note: In summary, no, the rules are not the same > everywhere in the USA. In almost every case you need a '1' before a > ten-digit number. In the case of seven-digit numbers it varies > according to the numbering scheme used by the local telco. The telcos > usually begin using '1' in front of seven digits when their supply of > prefixes without a one or a zero as the second digit begins to run > short. A one or zero in the second digit of a three digit number here > usually indicates an area code instead of a local exchange code. Using > '1' first allows an extended set of exchange codes. I'm confused by what the Moderator is saying here. When an area code runs out of NNX exchanges and starts introducing NXX exchanges, it seems that changing intra-area long distance dialing from 7D to 1+7D is exactly the *wrong* thing for the telco to do, because it introduces ambiguity. Timeouts would thus be needed to distinguish between, say, 1-312-4567 and 1-312-456-7890. Have any telcos actually pulled such a stunt? Why didn't they just go directly to 1+10D dialing, which has no such ambiguity? It would be a shame if some places were converting from 7D to 1+7D at the same time when many other places are "doing the right thing" and converting from 1+7D to 1+10D. In answer to our Danish friend, no, the rules are not *currently* uniform. But it appears that all non-conforming telcos will have to change by 1995 at the latest, when NXX area codes start appearing in the NANP. There will then be only two ways to direct-dial a number: NXX-XXXX, and 1-NXX-NXX-XXXX (*). Most of the NANP already seems to use these rules, but there are still a lot of exceptions. As far as intra-area toll calls go, there appears to be some variation allowed even under the new plan. Some telcos require NXX-XXXX, and some require 1-NXX-NXX-XXXX. Anyone out there know of any telcos that accept *both* forms? Which one is recommended by Bellcore (if it cares)? (*) There is currently at least one place (Dallas & Ft. Worth, Texas) where NXX-NXX-XXXX dialing is allowed for calls which cross an area code boundary but which are local; LD calls there use the usual 1-NXX-NXX-XXXX format. I don't know if this setup will be permanent, or if it will (or has) spread to many other areas. In such areas, of course, the telco must take care not to introduce any exchanges that use the same three digits as the adjacent-but-local area code. Bob Goudreau +1 919 248 6231 Data General Corporation goudreau@dg-rtp.dg.com 62 Alexander Drive ...!mcnc!rti!xyzzy!goudreau Research Triangle Park, NC 27709, USA [Moderator's Note: We seem to be back to where we were a couple weeks ago on this: What you think about the '1' on the front depends on what your telco has pomoted with /without it over the years. PAT]
goudreau@dg-rtp.dg.com (Bob Goudreau) (03/05/91)
> I'm confused by what the Moderator is saying here. When an area code > runs out of NNX exchanges and starts introducing NXX exchanges, it > seems that changing intra-area long distance dialing from 7D to 1+7D > is exactly the *wrong* thing for the telco to do, because it > introduces ambiguity. Timeouts would thus be needed to distinguish > between, say, 1-312-4567 and 1-312-456-7890.... > [Moderator's Note: We seem to be back to where we were a couple weeks > ago on this: What you think about the '1' on the front depends on what > your telco has pomoted with /without it over the years. PAT] No, it has nothing to do with that. It has everything to do with ambiguity. If the telco allows intra-NPA long distance dialing using 1+7D, and the telco also uses NXX exchanges (i.e., exchanges that look like area codes) within that NPA, then how does the switch know how many digits will follow "1-NXX-"? Answer: the timeout kludge. Yuck. If the telco were reasonable, it would replace 1+7D with either 1+10D or with 7D, both of which are unambiguous. Bob Goudreau +1 919 248 6231 Data General Corporation goudreau@dg-rtp.dg.com 62 Alexander Drive ...!mcnc!rti!xyzzy!goudreau Research Triangle Park, NC 27709, USA