Heres a reply a mate wrote about this subject on his site a while back
Tip 1: 112 is the international emergency number for mobile phones

It is true that, in many parts of the world, dialling '112' from a mobile phone will connect the caller to local emergency services. The number '112' is the international emergency telephone number for GSM mobile phone networks.
112 is the International Emergency Number for GSM mobile phones
An Australian government webpage dealing with emergency calls notes:

When dialling '112' on GSM mobile phones, access is provided regardless of the presence or validity of the SIM card within the phone, or whether the keypad is locked. The '112' number cannot be dialled from the fixed network.

•'112' can be dialled anywhere in the world with GSM coverage and callers will be automatically translated to that country's particular emergency number.

•A caller is able to connect to the emergency services answering point if GSM mobile coverage is available from any carrier's network at the location of the call.
However, because '112' is primarily integrated with the GSM network, it may not work if the phone is connected to another type of network such as CDMA. The Australian Government webpage also notes:
In Australia, it is a mandatory obligation for '112' to be built into GSM mobile phones. While this is not the case with CDMA mobile phones - as the international standards for CDMA do not require '112' - some mobile carriers have enabled '112' access in their CDMA mobile phones. However, this service does not have the extra capabilities, such as roaming and PIN override, that '112' has on GSM networks. For further details regarding '112' access on a CDMA phone, consumers should talk to their mobile service providers.
Therefore, while it is certainly useful to know about '112', mobile phone users should be aware that this emergency number may not work in every part of the world or for every mobile network.

Moreover, some circulating messages about '112' claim that the number will work even if there is no mobile phone signal or will automatically divert to a satellite phone system. However, this information is false. While ‘112’ will attempt to connect to any available network, it certainly will not work if no signal at all is available.

Finally, it should also be noted that, in the European Union, '112' is the emergency number for all Member States and will work from both mobile and fixed phones.

Tip 2: You can unlock your remote keyless entry enabled car from a long distance via a mobile phone call.

This tip has generated vast amounts of, sometimes heated, debate. A lot of people swear that the trick works while a great many others claim that it does not and is technically impossible. I suspect that at least some of the people who claim that the technique works have conducted their experiments without realizing that they are actually still within unlocking range of their vehicles. The range of the entry systems may be significantly greater than experimenters realize. Thus, people may actually believe that they have unlocked their vehicle via their mobile phone when they have in fact done so in the normal way via their remote device.

That said, a great many posters claim to have used the technique from many kilometres distance. In truth, logic and common sense compellingly suggest that the trick is not technically possible. Keyless entry systems work on radio waves, not sound, so it is very difficult to believe that the unlock signal could be transmitted via a mobile phone call, especially since mobile phones and keyless entry systems work at entirely different frequencies.

However, the volume of conflicting reports on the issue means that, at this point, it would be premature to state categorically that the trick will never work under any circumstances. Some have postulated that the technique might be possible with certain keyless entry systems and/or phone services or combinations thereof and this may indeed be the case. This scenario would explain why the technique might work for the few but not the many. Coupled with false conclusions made from invalid experiments, these exceptions might explain why so many people so vehemently claim that the trick actually works in spite of the evidence against it.

What I can say conclusively is that I have personally testing the technique with several keyless entry/mobile phone combinations without any success whatsoever. And, even if the technique does sometimes work, it seems clear that in the great majority of cases, it does not, so this tip is actually rather pointless.

Tip 3: Press the keys *3370# to activate hidden battery power on your mobile phone.

This "tip" is totally bogus. You cannot activate hidden or reserve battery power by keying in *3370# or any other code sequence. The code '*3370#' can be used on some Nokia models to activate Enhanced Full Rate Codec (EFR). Ironically, since this code activates the best sound quality on the phone, the change will actually reduce the length of time that the battery will last before recharging is required – in practical terms the complete opposite of what the tip suggests.

Entering the code has no effect at all on brands of phone other than Nokia.

Tip 4: Press the keys * # 0 6 # to check your mobile phone serial number.

This does work on many kinds of mobile phones. Entering * # 0 6 # displays the phone's unique International Mobile Equipment Identity (IMEI). The IMEI is also usually printed underneath the battery.

If a phone is reported lost or stolen, the IMEI can be used to disable the phone, thereby making it impossible for thieves to use it.

A Wikipedia entry about IMEI notes:
When mobile equipment is stolen or lost, the operator or owner will typically contact the Central Equipment Identity Register (CEIR) which blacklists the device in all operator switches so that it will in effect become unusable, making theft of mobile equipment a useless business.
However, CEIR blacklisting is not always effective because it is sometimes possible to reprogram stolen phones with a new IMEI and, although in theory every IMEI is supposed to be unique to a particular device, this is not always the case in practice.

Certainly, it could be wise to record your IMEI just in case you need it at some point in the future. But it should be noted that you do not actually need to have your IMEI at hand to have a lost or stolen phone deactivated. Virtually every provider will have the facility to quickly deactivate or disable your mobile phone account, even if you cannot provide the phone’s IMEI. If your phone is lost or stolen, contact your provider and explain the situation. They should be able to immediately initiate methods that will ensure that thieves cannot use your phone account to make calls.
(mon bison powered by magnets, Thu 31 Jul 2008, 14:30, Reply)