Ceri JC

The serial no. thing is a nice idea, but it only blocks your phone where it is registered (in most people's case, the UK). Would be good if it weren't for the fact that well over 90% of mobile phones that are stolen leave the country on ship in containers destined for the east, in particular India.

I don't know about the battery reserve thing on othere phones, but it doesn't work on my (ubiquitous) Nokia 6021.

The remote keyfob thing sounds like a nice idea (and from a theoretical POV could be possible if both your car and phone were bluetooth enabled and paired- could be a nice feature to see in future if phone and car companies collaborated on the issue. Given Ford's recent integration of bluetooth and phone pairing in the USA, it looks like this may well happen in the not too distant future), but I think it's nonsense. I've not tested it, but I don't see how it could possibly work. For it to be transmitted from a landline of someone with the keys it would have to be based on very high pitched sound, which even if your phone's speaker could reproduce, would be shaved off to save bandwidth on the phone network (low frequency sounds are also removed). It's technologically possible if your keyfob worked on IR and both the sending and recieving phone also had IR built in, but I don't believe phones transmit background IR as a matter of course (if they do you could use the same trick to open remote garage doors, change tv channels, etc.)

112 thankfully is correct and can sometimes work when a phone reports zero coverage (useful if hiking).