International dialling codes
The internet and email have made it much easier to keep in touch with family and friends wherever they are in the world.
But despite our increased reliance on modern communications, there may be still times when we'd like to call overseas.
Our international dialling code checker (pdf) will let you know the country code for everywhere from Australia to Zambia.
To use it simply click open up the pdf and press the Ctrl and F keys at the same time.
Then type the name of the country you're looking for into the search box to find the code you need.
So, for example, if you typed in Guatemala it would tell you that the code is 502.
Similarly, if you typed in the number 886 you'd find that this is the code for Taiwan.
Telephone facts and figures
It took at least ten days to send messages between the US and Europe before the first transatlantic telegraph line was successfully laid in 1866.
The first commercial transatlantic telephone service – using radio - began in 1927 between New York and London.
It wasn't until 1963 that you could dial another country from the UK without having to go through the operator. Even then the new service only operated between London and Paris.
You couldn't direct dial the US until 1970 when International Direct Dialling was introduced between London and New York. Within a decade IDD services had been extended to cover over 90% of UK phone customers and reached more than 80 overseas countries.
If you need to ring the Vatican, the dialling code is actually the same as Italy's – 39.
Country codes are assigned by the International Telecommunications Union. The telecoms section of its website contains information about the numbering plans in different countries.
Initially countries with more telephone users such as the UK or France were given two-digit codes (44 and 33 respectively) while smaller countries like Iceland were given three digit codes.
Regularly calling abroad can be expensive but there are ways you can cut your bills.
Firstly, you should ask your phone company for information and advice on its charges for international phone calls.
If you make a lot of calls abroad, it might be worth asking if it has a specific international calling package. Typical packages will cover the cost of calls to certain destinations for a monthly fee.
However, make sure that the country or countries you want to call regularly are included in the package. Also, with some packages, only the first hour of a call is free.
If you're a BT customer, there are also a number of phone companies that offer cheaper international calls via indirect access (IA) or carrier pre-selection (CPS) services.
With these you still pay BT for your line rental, but you can choose for some or all of your calls to be routed via another phone company and you pay them for the cost of the calls.
Pre-paid calling cards also offer an alternative way of making national and international calls to a variety of destinations.
Calls are then made from any fixed line or mobile phone by dialling an access number (020, 0800, 0845, 0870 and 0871 access numbers are commonly used) and then by typing in the unique PIN number that is printed on the back of the calling card.
You can also use VoIP - or more precisely Voice over Internet Protocol – which allows you to make phone calls over the web.
You can make calls from PC to PC – which are usually free - or you can use VoIP to call a traditional landline or mobile.
You'll need a headphone and microphone – or dedicated VoIP handset - which you plug into your PC or you can plug in a traditional home phone using a VoIP adapter.
You can also use the built in microphone and speakers in many computers, particularly laptops. You then download the required software from your chosen VoIP provider, although you should check that it is compatible with your computer.
There are different types of call plan so it's good to shop around and do your research beforehand, taking into account how you want to use the service.
Calling from abroad
We've also got advice on keeping your bills down when ringing home from abroad.
You can check out our ‘Ask Ofcom a question' facility on the top right-hand corner of the home page. It contains answers about using your mobile on holiday, texting whilst abroad, charges for international data roaming servicesand who pays when you receive a call overseas.
Why not also watch our advice video on using your mobile abroad. It gives tips on what you need to consider before you travel, as well as advice on using mobile phones and downloading data abroad.