From: Jay Hennigan (jay@west.net)
Date: Sun May 23 2004 - 02:35:27 GMT-3
On Sat, 22 May 2004, ccie2be wrote:
> See the Command Reference for Destination Pattern
>
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fvvfax_r/vrf_d.htm
>
> I came across this while going through the IE practice labs, but I still
> don't know what kind of number a number without the "+" in front is or how
> the rtr behaves differently.
A "+" in front of a telephone number syntactically means, "put your local
country's code for international dialing here."
It so happens that the North American Numbering Plan is Country Code 1,
and the digit 1 is also generally used within the NANP to denote that
a fully qualified 10-digit number including area code follows. So for
calls to the US, +1 408 555 1212 is parsed as "Country code 1, NPA 408,
NXX 555, line 1212 which happens to work. A number in Great Britain would
be written as +44 2222 3333 4444 (for example, probably not a real number).
This means country code 44, phone number 2222 3333 4444.
To dial from the US, one would send (to the PSTN) 011 44 2223 3333 4444 (#)
The 011 says "country code follows", and differs from country to country,
so is replaced by the "+' symbol. As international E164 numbers are of
varying length, the "#" symbol may sometimes be used to specify
end-of-dialing, otherwise there is a timeout for manually entered numbers.
Electronically entered numbers such as those generated by routers and cell
phones with the "Send" button need no such end-of-dialing delimiter.
I'm dating myself here, but in the good old days certain colored boxes
built in garages had a buttons labeled KP and ST, and the ST was used as
an end-of-dialing delimiter. KP was start of dialing. IIRC, 1100+1700 and
1500+1700 respectively. TTBOMK this hasn't worked for a long time but
it was fun while it lasted.
So, a fully qualified E164 number includes the + to denote that the leading
digits of the number are a country code.
An intelligent system located within the NANP would see + 1 NPA-NXX-XXXX
as a same country number, as the "1" after the "+" matches the local
country code. Similarly, an intelligent system in Great Britain would
parse + 44 xxxxxxxx as a same-country call.
A system in the NANP seeing + 44 xxxxxxxx would realize that it is an
international call for country code 44, and route it appropriately. The
reverse is also true.
So, "+" signifies, "Complete E164 number including country code follows".
-- Jay Hennigan - CCIE #7880 - Network Administration - jay@west.net WestNet: Connecting you to the planet. 805 884-6323 WB6RDV NetLojix Communications, Inc. - http://www.netlojix.com/
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