RECENTLY, I HAD a series of unsatisfactory encounters with a disembodied voice. I was living in the United States at the time and I used to phone Australia using a pre-paid phone card from the US Postal Service. It was good value. I could chat for quite a long time for my $10, even if I had to endure, every time I dialled, an irritating ad for US Postal.

When my card ran out I found that the supply of phone cards in the shops was erratic. Sometimes you could buy global cards, sometimes you couldn’t. But as it says on the back of the card, all you have to do to add value to the card is to ring the number supplied and follow instructions.