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 mobilephone networks

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.