Just for the record, bluejacking is not the same as hacking into someone's phone, more it's a mischevious way of sending a message to a phone - see
http://www.bluejackq.com/what-is-bluejacking.shtml
bluetooth can, I believe, be used to hack into unsecured phones, but bluejacking is something entirely different. It's definitely not meant in a harmful way.
As to zephyras1's mobile strangeness, I have no idea how it happened but can say that I have had something which may be along the same lines.
When I visit Edinburgh, I somehow start getting calls to my mobile number from other people around Scotland.
These callers' numbers are not in my phone book, and when I answer, they usually sound confused that the person they dialled hasn't answered, and ask to speak to them.
These people all insist they've dialled the correct number (not the same one as mine, or even close at all) and I don't think I've ever had the same person call more than once.
This continues for the duration of my stay and for a few weeks after I return home, after which it stops as mysteriously as it started.
The people who call have, on occasion, accused me of stealing their friend's mobile, as they absolutely insist they've dialled their friend's number and not my own.
My mobile operator says that the entire situation is impossible and cannot happen under any circumstances, and yet it has occured twice, about 18 months apart.
It's only ever happened with Edinburgh though.
My own suspicion is that there's just something screwy going on with the mobile network