Using a Plus to Simplify International Dialing

By Ben Gross
in

When I travel out of the country, I usually test out new VoIP services both for calling back to the states and receiving calls while I am traveling. I consistently find that while the rates for VoIP services are very attractive the usability and flexibility leaves a lot to be desired when I am on the road, particularly when no network connection is available.

Depending on the length of my stay, I purchase a prepaid SIM to use in a spare unlocked mobile phone so that I can make and receive local calls at local rates. Since most countries outside of the US offer free inbound calls, having a local SIM is even more attractive although navigating voicemail prompts in another language can be challenging. I often use on of the VoIP services to forward a US number to my international cell phone number so that I can let friends and family reach me without incurring international charges on their part. Rates for calling international mobile phones range from $0.15 to $0.30 a minute so be careful who you give your forwarded number to if you try this method.

Calling from multiple devices and multiple services is where plus dialing standard becomes important. People who make regular calls overseas from a mobile phone or a VoIP service will likely be acquainted plus dialing. However, I find that there is quite a bit of confusion about what plus dialing is and how it works from people who have only called internationally using landline phones. For those interested in the gory details, the official specification dialing using the international prefix symbol (commonly known as a plus) is the ITU specification E.123 : Notation for national and international telephone numbers, e-mail addresses and Web addresses

If you want to dial a phone number in another country using a standard landline phone, you need to dial an additional set of digits. Lets pick an imaginary number in the Netherlands 011 31 20 00012345 as an example. The breakdown for this number follows: The international dialing prefix is 011 for the US, The country code for the Netherlands is 31, the city code for Amsterdam is 20, and the remainder is the local number. We are now used to dialing ten digits for long distance call in the US. For example, (415) 555 1212 (country code, area code, local prefix, last four digits).

The problem is that the number you call depends on what country you are calling from. Dialing the same number in the Amsterdam from Brussles would require a different a slightly different number 00 31 20 00012345. Also, in many countries there is a local digit added to the numbers for in country dialing, so the number might look like this 31 0 20 00012345.

Plus dialing is a more straightforward option for mobile phones, VoIP phones, and newer business phones. With plus dialing the phone network can assume that the number is a complete international number and treats the same way no matter what country you are in when you dial the number. The one constraint is that your phone must me able to dial a plus.

Under the new system, you dial a plus, the country code, city code, and then the local number. For example, +31 20 00012345 as opposed to 011 31 20 00012345 or 31 0 20 00012345. Dialing a US number would take the form of +1 415 555 1212 . The nice thing is that once you have your numbers in plus dialing format you don’t have to worry about variations when you travel. You can dial the same number from your cell phone and a VoIP call such as from Skype. Most cell phones can dial using a plus sign, although you might have to search for the correct key combination. Most landline phones do not have the ability to dial a plus.

I normalized my entire address book so that all numbers are internationalized. This way no matter what system I use to dial (cell, VoIP, etc) it will be correct for wherever I am. I synchronize my address book with my mobile phone and use the same address book for dialing with any VoIP services so I only need to store and use one form of the phone number. I will talk more about cleaning and synchronizing address books in a future article.

Published August 14, 2009