By: David Currier On: October 17, 2011 In: Contact Center Comments: 0

Something important crashes to the floor from the desk in the rush to get to your phone for the executive conference call you were supposed to join three minutes ago. After looking up the number and quickly punching it into the handset, you hear “bee-Bee-BEE. Your call cannot be completed as dialed. Please check the number…”

Regardless of the reason, dialing a number that does not connect can be very frustrating. After many questions and frantic calls for support, I decided to write this post to help dispel some of the mystery that often surrounds how telephone numbers are composed and dialed.

The Basics
Virtually all telephone numbers you will encounter follow the E.164 numbering plan and are composed of three basic parts:

  • Country code
  • Area code
  • Local number

How you dial each number is determined by where you are located.

Phone Numbers in the United States
The U.S. along with a couple dozen other countries participates in the North American Numbering Plan (NANP) which basically states that numbers within it will use the following


  • + – indicates that an international access code will need to be added when this number is dialed from a country outside the NANP
  • 1 – the country code used by the NANP
  • NPA – an area code within the NANP
  • NXX – central office exchange code, the first part of each local number managed by a given carrier
  • xxxx – subscriber number, the final portion of each number assigned to a customer

While there are a variety of special classifications (emergency, information, toll free, etc.), phone numbers within the NANP will generally fall into one of three categories:

  • Local
  • Long distance
  • International

Dialing Local Numbers
Unfortunately, there is no set rule for how local numbers should be dialed. Each area will have its own rules. However, they will generally allow and/or require one of the following:

  • 7 digits – dial the exchange and the local number only to call another number within the same area code
  • 10 digits – in a region covered by more than one area code, it may be necessary to dial both the area code and the local number
  • 11 digits – in some cases, a one must be added to the beginning of the number followed by the area code and local number

Dialing Long Distance Numbers
In most countries outside the NANP, a trunk code of zero is required before any number not within the local calling area. Within the NANP, the number one preceding the area code is generally required as the trunk code to call a number outside of the local calling area. This can be especially confusing because the NANP country code is also the number one.

If dialed from within the NANP, the number would be written as:

1 (213) 213-2134

Note: the parentheses indicate that the area code may be optional when dialed from within its local calling area. In fact, (unlike many other countries), dialing the full phone number often will not work when dialing a local number.

If dialed from a country outside of the NANP, it would be written as:

+1 213 213 2134

Dialing International Numbers
In general, dialing an international number requires an international access code. For example, to dial a number in the United Kingdom, a U.S. caller would dial:

011 + 44 + area code + number

For calls placed from within the NANP to a country outside, 011 is the access code to indicate that the call is an international call and should be routed as such.

A common mistake is to include (or even dial) the trunk code as part of the international number. For example, a London caller might dial something like the following as a local number:

020 xxxx xxxx

It should NOT be written or dialed as:

+44 (0)20 xxxx xxxx

This is because the zero immediately preceding the area code is ONLY dialed from within the United Kingdom. From the United States, this number would be dialed as:

011 44 20 xxxx xxxx

Also keep in mind that newer phone systems and many mobile phones would allow this number to be stored in the following format so that it can be dialed from anywhere in the world:

+44 20 xxxx xxxx

More Information
If you are unsure how to dial an international number, I highly recommend visiting