[news.bbc.co.uk]

Your mobile phone is a beacon – a radio transmitter in a box. Therefore it is possible to trace the signal and work out where it is.

There are now several web companies which will track your friends’ and family’s phones for you, so you always know where they are.

But just how safe is it to make location details available online?

[…]

I attempted to find out, using regular contributor Guy Kewney, an independent technology journalist and, for one day only, human guinea pig.

I sent him on a tour of London. He could go anywhere he wanted, and I planned to meet up with him later and tell him, hopefully, where he had been.

Guy did not know that when I borrowed his phone for a few minutes earlier in the day, I took the opportunity to register it on one of the tracking services.

Continues at [news.bbc.co.uk]