Using a Plus to Simplify International Dialing

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 user experience and flexibility is often lacking when I traveling, particularly with limited network connectivity.

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 one of the VoIP services to forward a my United States phone 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 often confusion about what plus dialing is and how it works from people who only dial international numbers using landline phones. For those interested in the 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 extra digits. Let’s 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, which corresponds with the country code, area code, local prefix, and 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 Brussels requires 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 phone number in the United States 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 the plus symbol, although the correct key combination is not always obvious. Most landline phones cannot dial a plus.

I internationalized my entire address book, so the number will be correct independent of my current location. Since I synchronize my address book with my mobile phone and my VoIP soft phone address book, I only need to store and use one form of the phone number.

* This article originally appeared as Using a Plus to Simplify International Dialing in my Messaging News “On Message Column.”