I recommend the World Telephone Numbering Guide.
Here is a list of all telephone area codes ("claves LADA") in Mexico, from the Mexican government: http://www.sre.gob.mx/austin/Util/LadasMexico.html (The column labeled "clave actual" is the current area code. The telephone country code for Mexico is +52, and you must also insert the prefix '1' between the country code and the area code when calling a mobile phone or cell phone.)
(see the related links)
Try the BT website. You can also get a full list from Ofcom, the UK telephone regulatory agency, or from Wikipedia. See the related links.
Yes a telephone directory is a telephone book. Which includes listings of all the numbers of people in a certain area. I myself would consider a telephone directory any list or book that includes a list of people and phone numbers that are in a certain area.
AnswerOfcom are the definitive source for this information, as the official regulator.There are also other more user-friendly sites around.
Telephone country codes are one-, two-, or three-digit codes identifying a country or external territory. For a complete list, see the related links. Some countries have separate codes for mobile phones, but others do not.
See the related link for a list of area codes in North America (USA, Canada, etc.).(see related links)
The related link provides a list of telephone country codes.
You have to know what area in the Philippines you want to write to, the best I can do for you is provide the site that gives you all the zip codes for the area your looking for, search the site and find the exact area.Philippines ZIP Codes Directory Complete list of All Postal ZIP codes in the Philippines and Telephone Area Codes list with a detailed Philippine map.http://zip-codes.philsite.net/
There is a list of area codes for the US and Canada on LincMad.com; see the related link.
Try countrycode.org. There, you can search for any country code that exists by name or number. If you try allareacodes.com you can get any area code within the United States and territories.