Short version: write every number with a plus and a country code, and never bake an exit code into a number you save or share. The checks below are the reasons, in the order you will need them.
Before you dial out
- Know which exit code your phone uses. The exit code is the signal to your own carrier that the digits that follow are a country code and a foreign number. It is picked by each country, not by the ITU, so it is not the same everywhere. The US and Canada use 011, much of Europe uses 00, and a good number of countries elsewhere do too.
- Do not trust a list of exit codes from memory, mine included. Japan has used 010 and Australia 0011, and some countries let customers choose between carrier prefixes. Carriers add and drop options, so a list goes stale faster than a guide can be updated. The plus sign avoids the question.
- Use the plus on a mobile. The phone replaces it with the right exit code for the network it is registered on: 011 in Chicago, 00 in Madrid, 0011 in Sydney. You do nothing different and the saved number stays valid in every country.
- Dial the exit code yourself on a landline. Landlines, many office phone systems and some old payphones do not understand a plus. At a desk phone abroad you need the local exit code, and the hotel front desk is the quickest way to learn it.
- Never put a 1 in front of 011. The 1 you dial for domestic long distance is a different thing, a trunk prefix that only works inside the US and Canada. It is also the country code of the North American plan, so one digit does three jobs, which is a fair summary of why this topic confuses people. Each piece of an international call has its entry in the glossary of international dialing.
- Drop the leading zero of a foreign number. Many countries print a domestic trunk prefix, often 0, before the area code. Once a country code is in front, remove it: a number printed 0151 1234 5678 in Germany becomes +49 151 1234 5678. A kept zero is the most common reason a copied foreign number fails.
- Keep numbers you may need abroad in the plus form, and fix the others first. A contact saved with a bare ten-digit number, a stray 1 or a baked-in 011 is the one that lets you down in a taxi in another country. Ten minutes of cleanup before a trip is cheap compared with that.
- Check for a country code that is already there. A number copied from a foreign site may already start with its own code, and adding a second one is the next most common failure.
Before you give your number to someone abroad
- Write it as plus, 1, area code, seven digits. For a New York number that is +1 212 555 0100, never 1-212 555 0100 and never 011 1 212 555 0100. The first works from any phone that accepts a plus, while the other two work only from a specific country, and the third is wrong for most senders anyway.
- Explain the zeros in 00 if they ask. It is not part of any number. The 011 is not part of the US number either. Both belong to the act of leaving a network, so the same digits that start a call from one country mean nothing from another.
- Offer the landline version only in words. If someone might dial from a hotel room phone, add a sentence saying the exit code is 011 from the US and usually 00 from many other countries, and that they should check their own. The ready-made wording for this sits in the page on dialing the US from abroad.
- Save your own copy the same way. A contact entry in the plus form is the one version that does not need updating when you or the other person change country. The steps are in saving contacts in international format.
Before you travel, and when a call comes in
- Test one call from home. Place a short call to a foreign contact using the plus sign, so you know the format works before the plane does. A failure at home costs nothing and a failure at the arrivals gate costs time.
- Ask your carrier about international calling and roaming in writing. Plans differ on calls, texts and data, and some prepaid or business lines block international calls until you switch the feature on.
- Write the hotel's own dialing instructions on a card. Room phones follow the hotel's configuration, which may want a digit for an outside line before anything else. A card in your pocket beats a fast busy signal at midnight, and the recorded message that follows a failed attempt is usually worth hearing to the end.
- Wait for the foreign network name. When your phone shows it, the phone has registered and will translate the plus for that country. Make your first call a short one to somebody who expects it.
- If a call fails, check in this order. Number format first, roaming setting second, signal bars last. The first two are the common causes and take seconds to fix.
- Treat an unfamiliar foreign code as unknown, not dangerous. Many foreign calls are legitimate, but some are bait to make you call back at a high rate. If it is a +1 code, read calling Canada and the Caribbean. If it is another code, find the country on the calling codes cheat sheet.
- Do not call back an unknown foreign number just to find out who it was. A real caller leaves a message or sends a text. Curiosity is exactly what a return-call lure depends on.
Next in the book900 numbers and pay-per-call prefixes: nine myths, checked