h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

This item has been shrinking ever since its conception.

The original models were the size of a medium sized suitcase. Today you can have one small enough to fit into the pocket of a small child wearing a pair of tight fitting jeans. There are estamates that by the year 2010 the mobile phone will be inserted into the inner ear at birth.

For now though, the general use for these hand held communication devices is to recieve useless and intrusive messages from someone you probably wouldn’t normally speak to on a daily basis.

One of there majour purposes is to embarass the owner in the most public of situations.
For example, a train crammed full of commuters.