While this is a great tip, a better tip is to remember that 112 is the Global GSM emergency number. It's part of the GSM standard so will work on any GSM phone in any country in the world. That way, you don't need to worry whether someone has applied the correct Registry Hack or if you're travelling, what the local Emergency Services' phone number is.
If you pick up a mobile phone in any country, and need to dial the emergency services use 112. Many phones don't even need to be unlocked.
It will even work in many countries without a SIM card in the phone.
See the Wikipedia article for more details:
http://en.wikipedia.org/wiki/Emergen...lar_telephones