Hi. Yeah. Yeah. Yeah. Right. Bye.

Mobile phones are small machines which let you talk to people far away who have similar machines. They are usually owned by people who spend most of their time travelling foolishly long distances in order to meet other people who have travelled foolishly long distances, which makes one wonder why they don't simply call each other on their mobile phones in the first place.

One unwanted side effect of mobile phones is that they take the privacy of a phone call and thrust it into other people's faces, even though they never asked for it in the first place. The privilege of listening to one half of someone else's conversation while being crushed in the rush hour crowds is one of the great pleasures of life, though oddly enough very few people seem to see it that way.

The man with the penetrating braying laugh is getting on the train, and you just know that he's going to sit across the aisle from you. In the old days, the worst you could expect was an inane conversation or a penetrating sniff, but now you can be dead certain that within minutes he'll have pulled out his mobile phone and be telling somebody which train he's on. So far, so good, and not a bad idea in a put-the-dinner-on-love sort of way. However, with a probability directly in proportion to the grating loudness of his voice, he will then launch into the most extraordinarily mundane conversation which everybody in the carriage is forced to follow word for word simply because it is so loud.

One of the worst fears of the listeners, of course, is that their own phone might ring, leaving them whispering, red-faced in the corner as the imagined assembled eyes of the carriage bore into their embarrassed heads. The reason is, of course, that almost all of us carry mobiles, especially the increasing numbers of migrant IT workers who move about from place to place and who do not necessarily even own a permanent landline. Annoying as they are in the wrong hands, they are so wonderfully useful. Worried about your kids or parents? Give them a mobile. Worried about breaking down in the rain or losing your way on the moors? Take a mobile. Lost on the way to a friend's house? Ring them from your mobile.

Mobile phone conversations also allow you to laugh loudly at jokes no-one else can hear; to pretend to be talking about a really important business deal when in fact you're negotiating the delivery date of the next box of paper clips to the stationery office; to develop and nurture large, unidentified lumps behind your right ear; and, most importantly, to feel wanted.

The best thing about the mobile phone, however, is that it replaces the land-line phone, which has a long wire attached at the bottom so that you can trip over it in the middle of the night when you really need a drink of water from the kitchen. Despite this advantage, the first time you should use a mobile phone is when it's freshly out of the wrapper, when you should call another phone three feet away, just to check that it's working.