[GreenKeys] Plus signs

[Eric Scace K3NA]

I worked (too) many years with the ITU on international standards for landline communications as a member of the USA delegation and, from time to time, chaired various committees and working groups.  That included some work on what are called "numbering plans".

Back in the day, "+" was adopted as an international convention to use when writing a complete telephone number.  "Complete" here means:

-- country code
-- national area/regional code (if one exists)
-- local number.

Hyphens or spaces can be used to separate the groups of digits for readability.

Thus, my phone number is properly written as "+1-617-712-1523":
   1 -- country code for much of North America (USA and Canada)
followed by the National Number:
   617 -- area code for Boston
   712-1523 -- local number (typically a central office code and a subscriber number).

In parts of the world where the area/regional code may be omitted for local calling within that region, the code is placed in parenthesis:
   +49 (69) 797-6600
"+49" is the country code for Germany.  "(69)" is the regional code for the area around Munich.  If you are in Munich, you can just dial the local number 797-6600 to connect to Siemens' international switchboard technical support.  If you are in another part of Germany, you must include the regional code; e.g., dial 0-69-797-6600.  A single "0" prefix in Germany indicates the number that follows is the full National Number (with its regional code).

Prefixes vary from country to country, although recommendations exist to provide some degree of uniformity.  "0" is very common as the prefix indicating that a full National Number follows.

When dialing my number from another country, one inserts that country's international access prefix in place of the "+".  The preferred international access prefix is "00".  USA and Canada are notorious exceptions to the use of "00"; here one can use:
   011 -- direct dialing without an operator
   001 -- international dialing via the operator (e.g., for reverse-charged calls).

Another variation between countries is the choice between "open" and "closed" national numbering plans.  USA/Canada uses a closed numbering plan, where all assigned National Numbers are 10 digits.

Many other countries (Germany, for example) use a open plan where some numbers are longer than others; e.g.,
   +49 (89) 636-00
is Siemen's Munich office switchboard, while
   +49 (89) 636-32474
reaches the investor relations desk.  (I don't work for Siemens; I'm just poaching their numbers off the web to use as an example).  So here, in three examples, we have seen German national numbers that are 5, 7 and 8 digits long.

International country codes are 1, 2 or 3 digits long.  USA/Canada and Russia get the 1-digit country codes (1 and 7, respectively).

Regional codes within each country may be closed or open in length.  The UK uses open regional codes in its open numbering plan.

OK, I think I better stop.  It's probably more than you really want to know...

73,
   -- Eric K3NA