Sit down to write something about mobile phones and you open the proverbial can of worms. These things (mobile phones not worms) come with a bewildering array of features that can take some getting used to, especially if (like me) you’re over 20 years old.

This Nokia 6110 mobile phone features both a data connector and an infrared port.

One of the most popular features is the "Short Message Service" (or SMS), which is used for sending short text messages from one mobile phone to another (for the cost of a local call). What, you didn’t even know that your mobile phone could do that? Don’t feel bad – hell, my brother didn’t even know about the "Snakes" game on his Nokia 5110 mobile until given a demonstration by his 5-year old son!

If you don’t know about SMS, ask any teenager – they’re busily punching out messages to each other on their mobiles every day and racking up big bills in the process. It must be a goldmine for the telco companies.

For those who don’t know any teenagers, we’ll briefly explain how SMS works. It’s a very simple concept – all you have to do is scroll to the "Write messages" (or similar) area of your phone and punch in a short message using the buttons on the keypad. Then, when you select "send", you are prompted for the destination number (ie, the mobile number that you want the message sent to).

When you enter this, the SMS message is sent to the destination phone via the "message centre" of your mobile carrier. If the destination phone cannot be contacted, the SMS message is stored at the message centre and immediately forwarded when the phone reappears on the network.

The big advantage of this scheme is that the destination phone doesn’t have to be switched on when you send an SMS message. Instead, the message goes via the carrier’s message centre and the number for this is usually programmed into your SIM card when you buy the phone. If it isn’t, it’s simply a matter of obtaining the number and entering it yourself.