British forces in Afghanistan sent this festive message by e-mail
On Christmas Day, most of us pick up the phone and give our friends and family a seasonal greeting.
But for people in remote locations, sending a festive message is not always an easy thing to do.
Twenty years ago, the only options were a crackly long distance call or a letter sent six weeks early.
Today, advances in technology mean that even if you are in the middle of the ocean, or half way up a glacier, there is always a way to send a message home.
So rather than making a good excuse as to why this year's Christmas card did not arrive on time, here are some of the technological solutions on offer:
For many, this is the cheapest and easiest choice. Electronic mail covers the entire spectrum, from basic text message, through to sound and movie files.
As long as you have got an internet connection and a means of getting online, then an electronic season's greeting can be sent with just a few clicks of a button.
Researchers and staff with the British Antarctic Survey filmed this Christmas greeting and uploaded it to an ftp site.
SMS / TEXT MESSAGE
Short Message Services - or SMSs - are almost as versatile as e-mails, enabling users to send photos and short video clips, as well as traditional text messages.
The popularity of the service has skyrocketed in recent years. According to the Mobile Data Association, more than 1.4 billion texts were sent in the UK every week in 2008, which is more than the entire number of texts sent in 1999.
According to data from the Mobile Data Association, from Christmas Eve to Boxing Day last year, 6,466,506 video and picture messages were sent.
SMS is available anywhere there is a regular cellular network, although unlike e-mail, users have to pay for every message sent.
Oil workers in the North Sea may only be 100 miles from Britain, but in winter, it is one of the toughest and remote environments to work in
Internet telephony aka VOIP (Voice over Internet Protocol to give it its full name) is a way of transmitting voice communications over the web.
Although the first communication of someone's voice over the internet happened in the early 1970s, it wasn't until the late 1990s - when internet speeds rose from an average of 300 bits per second (bps) to 56 kilobits per second (kbps) - that it became a viable proposition.
Today, with a typical internet connection typically running at 3,000 kbps, you can now not only send speech over the net, you can send video too.
What's more, you can often use your VOIP package to dial into a public switched telephone network (PSTN), meaning you can make a call anywhere there is an internet connection, with only a minimal charge made by an Internet Telephony Service Provider.
However, unlike PSTN networks, quality can often be hit and miss and due to frequent distortion and delay, using VOIP to send a fax is very difficult.
Sam Davies, on the yacht Roxy, uploaded a Christmas greeting from the Southern Ocean, half way through the Vendée Globe round the world race.
Instant Messaging is a way of sending text messages (and in some cases, images) in real time across the internet.
Chat - or IMing - allows users to have a conversation between two or more people, or to send pending messages to a user, who will then get the message when they log in. Think of it as hybrid of e-mail and SMS in real time.
BLOGS & SOCIAL NETWORKS
For some, constant or regular access to the internet is impossible. One solution is either writing a blog or sending a electronic greeting through a social network site, such as MySpace or Facebook.
It does mean you can send a global message to everyone you know, although they often lack that personal touch.
A satellite phone can work almost anywhere in the world
Similar to a mobile phone, a satellite phone - or satphone - dials in using a satellite connection, rather than a conventional mobile network.
Modern handsets are similar in size to a regular mobile phone, although units installed in ships may have a directional dish that points at the closest satellite.
The only problem is that they need a clear line of sight to the satellite, so they perform poorly inside buildings.
As long as you can 'see' a satellite, you can get online with a B-Gan
In principle, this works in the same way as a satphone.
But rather than direct voice communication, it taps into the B-Gan (Broadband Global Area Network) at 492kbps.
It is also somewhat larger - about half the size of a conventional laptop. It work on land, sea, and air; BMI is currently trialling a system that would give air passengers with a Blackberry access to the internet.
Amateur radio is probably the oldest 'modern' way of communication
This is a free service operated by the British Forces Post Office and allows servicemen and women to receive typed letters in the field that have been written and sent over the internet.
Once the e-mail has been received, it is printed and put into a self sealing envelope and then sent out to the troops, along with the traditional mail.
On average, 100,000 e-blueys are sent each month, although this figure increases during Christmas and when roulement occurs ie when combat units go on a tour of duty.
Families of servicemen can also embed an image into the message, turning it into the eponymous picture-bluey.
VHF / SSB / HAM RADIO
If an internet connection is impossible, there are no telephone lines, and a post box is just a distant dream, then some people hook themselves up with an amateur radio.
Although operators can communicate across the globe, the range of available frequencies is limited, with the bulk of the radio frequencies occupied by military or commercial use.
At its most basic level, amateur radio operators - hams - use Morse code to communicate.
However, some sets can be used to talk to communication satellites called OSCARs (Orbiting Satellite Carrying Amateur Radio), as well as bouncing signals off the moon or meteor showers.
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