Re: [hylafax-users] Dialrules, local exchange dialing.

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Bill Campbell wrote:

> Has anybody put together a database of dialrules that deals with the issues
> of local vs long distance dialing by area code and exchange?
>  

Yes many times for different areas.

> Our local dialrules file is about 400 lines of mappings, some of which are
> mapping exchanges that were in our 206 area code to new area codes, but
> most of them are used to remove the ``1'' prefix from prefixes in other
> area codes that are local calls, and the rest add the ``1'' to exchanges in
> the 206 area code that are long distance calls.
>  

Your clients are going to, if they don't typo, enter in either a 
7-digit, a 10-digit, or an 11-digit number for domestic calls.  (In 
areas like Seattle dialing with a 7-digit number is, in my opinion, 
unsafe unless you're absolutely sure what area code the line is in that 
will be used to place the call.  But nonetheless clients will still send 
7-digit numbers.)  If, you don't want to make an assumption about an 
area code then you can reject calls with DestControls that don't have 10 
digits:

 ^[+][0-9]{0,9}$ RejectNotice = "Number too Short, need at least 10 digits"

Otherwise, you can use dialrules to add the area code for you (see below).

First off, you want to learn to use dialtest in order to work through 
the fine-tuning of your dialrules.

 dialtest -a 206 /var/spool/hylafax/etc/dialrules

Then start provide it possible numbers that clients may submit and see 
if dialrules accomplishes what you need.  If not, then adjust dialrules 
and try again.  So let's say that my area code is 206 and that my telco 
requires 10-digit dialing and that I am okay with assuming that 7-digit 
numbers refer to area code 206 and that the only exchanges that are 
local to me are 444 and 555 (yes, I know that this is an absurdly short 
local exchange list).  Then the dialstring portion of my dialrules file 
may look like this:

DialString := [
[-${WS}.]+ = ! strip syntactic sugar
[abcABC] = 2 ! these convert alpha to numbers
[defDEF] = 3
[ghiGHI] = 4
[jklJKL] = 5
[mnoMNO] = 6
[prsPRS] = 7
[tuvTUV] = 8
[wxyWXY] = 9
^[0-9]{10}$ = ${Country}& ! add country code for 10-digit dialers
^[0-9]{7}$ = ${AreaCode}& ! add area code for 7-digit dialers
^[+]${Country}${AreaCode}444[0-9]{4}$ = ${AreaCode}444& ! local call, 
strip the +1
^[+]${Country}${AreaCode}555[0-9]{4}$ = ${AreaCode}555& ! local call, 
strip the +1
^[+]${Country} = ${LDPrefix} ! long distance call, replace country code 
with long distance code
^[+] = ${IDPrefix} ! international call
]

What this does is it does the usual whitespace stripping and alpha 
conversions.  Then, if the number is 10-digits it adds a "1" to the 
beginning of it - because requiring people to know when to use a 1 and 
when not to use a 1 is silly - so everyone will dial 10-digits.  If it 
happens to be a 206444 or 206555 number then it will get processed 
further, otherwise there will be no more processing of this number. Then 
if the number is 7-digits it adds the area code to the front of that.  
There is no further processing of that number.  Now it takes all numbers 
that at this point say 1206444 or 1206555 and it strips off the 1.  At 
that point it's essentially done - replacing the country code wit hthe 
long distance code probably means nothing in your situation.  The last 
rule, international, probably is useless since nobody ever dials with 
canonical format.

Now, you probably can take that as-is but replace the two exchange 
examples with the hundred or so exchanges that are local to you.

> This wouldn't be a problem if the telco's switches were programmed to dial
> local numbers with a ``1'' prefix, stripping it for calls local to the
> exchange.

In my experience telcos very rarely support dialing long distance 
without the 1 or dialing local with the 1.  That's there way of making 
sure that you're aware that you're gonna get charged for the call.

> I haven't even been able to find anybody in our telco that could
> give me documentation on what's long distance, and what's local from our
> exchange.
>  

Getting that list is an absolute MUST.  When I was up in King County I 
found most of this list from the front of the big thick tree-killer that 
they called a phone book.  However, if you want to include (you probably 
don't as they're not likely to be fax) wireless numbers you're probably 
going to have to get this by requesting it by phoning them over and over 
and over until you get in touch with someone that can get it to you.  
Sometimes it takes me days of phone calls at various times in order to 
locate an employee competent enough to get that to me.  Usually the 
numbers in the front of the phone book are enough to get you going.

> Getting the dialrules file right has always been one of the biggest issues
> when installing hylafax at a new location.
>  

It's not fun, no.  I'm not sure that there's a better way, though.

> I've thought it would be nice to have xmlrpc server(s) which would return
> the proper prefix when passed the local and destination area codes and
> exchanges.
>
> Another option might be to have the hylafax send program call an external
> program, specified in the config file, that would take the called number as
> an argument, and return the proper dial string.

In any case you still have to obtain a list of exchanges.  I'm not sure 
that coding in dialrules is any harder than coding in shell or whatever.

Hope that helps,

Lee.


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