When Alexander Graham Bell first registered his patent for the telephone in 1876, nobody could have guessed the scale in which it would eventually revolutionise the way people communicate. Indeed, in the 21st century it's difficult to imagine life without the trusty telephone, especially now that the majority of people in the western world now have their own mobile phone.

The ubiquity of the mobile phone in modern society has led to a decline in the use of the traditional home phone, as costs have come down significantly in recent years. Furthermore, many networks now offer special ?roaming? features when travelling to certain countries, meaning any calls made whilst in that country are charged in exactly the same way as the country of origin.

But mobile phones are still, in general, more expensive when it comes to calling abroad and tariffs can vary greatly between network operators. Furthermore, through the widespread use of the internet, many people are required to retain a telephone socket in their home as a means to connect to the world-wide web, which may help to explain why landlines still have at least some part to play in the communication world, despite their obvious decline in use for their originally intended purpose.

Many people now choose to send an email instead of writing a letter, largely because it's free and more convenient. And whereas people once engaged in conversations remotely via telephone, more and more people are using online instant messaging services as it's also free and it enables people to be far more casual. It still allows people to communicate in real-time, but they can come and go as they please, picking up the conversation again minutes later and even invite other people to enter the conversation, much in the same way as a real conversation would work.

But there are still many situations that require the immediacy and intimacy of verbal dialogue, whether it is for business or to speak with a loved-one on the other side of the world. This is where internet telephony services come in. Commonly referred to as VoIP (Voice Over Internet Protocol), this allows people to speak through the internet using downloaded software and has proved particularly popular with people wishing to communicate with other parts of the world at a fraction of the cost of using a landline or a mobile.

But so many people these days rely on portability and being able to communicate on the move, anywhere, anytime. For this, many use an international calling card, which is prepaid and can be used from most public payphones and mobile phones. And then there is the which is available for Skype Pro subscribers on mobile phones and enables international calls at local rates.

So, there are many options open to people wishing to communicate in real time with any other part of the world, whether it's instant messaging on the World Wide Web, or internet telephony. And as with most modern technology, portability is still a key factor for many people, as they look to communicate with the global community anywhere, anytime without burning a whole in their pocket.