Here in the UK, the number to call in case of emergency is 999.
Also contrary to USA practice, they DO ask for your post code, which is pretty much the same as the zip code.

In case of an emergency at home, almost everyone knows their post code, however in case of say a traffic accident the person calling for help wont have a postcode for the accident site and this can cause delay.

The 999 call is answered by an operator who will enquire as to what service is required, the options throughout the UK being fire, police or ambulance.
In some parts of the UK other options are available in addition, such as the coastguard or mountain rescue.

A slight drawback of the UK system is that emergency calls are automatically routed to the emergency service in the geographical area from which the call is received.
If dialling from London and asking for "police" the call will be routed to the metropolitan police.
This can cause delay if assistance is needed in another area. For example a somewhat confused elderly person telephoned me about a gas leak.
I rang 999 for the fire brigade, but it took a bit of explaining as to why I was requesting that the fire brigade attended an address hundreds of miles away. Valuable time was thus lost, such incidents are however rare and generally the system works well.

Here's some advice applicable for calling from cell phones...

https://www.youtube.com/watch?v=XPZv_8dABfU

112 for emergencies works in a lot of countries...

Wikipedia's 112 Emergency telephone number page

Can anyone verify that the advice works in the U.S.? Particularly the part about the dialing 911 (here, rather than the 112 featured) actually activates a "hunt" if the phone isn't set to roam... or that the cellular call to 911 will gain priority on a busy network? I just haven't heard of any of that here in the U.S.

Every carrier is required by law in the US to pass 911 calls. I have personally had it work for me when my phone had no signal, but I was in another carrier's coverage zone. Remember that your phone has to have the same kind of radio (e.g. GSM) that the carrier uses on their towers.

Thanks Chaos.

I take partial exception to #5 in the original poster's link - "Follow the dispatcher’s instructions."

Usually this is good advice, however a 911 operator is ordinarily not a police officer and you have no duty to follow his instruction if, in your opinion, it would place you in danger. This was the case in a story I read -

https://www.denverpost.com/2012/04/02/de...-official-says/

- of a motorist who reported a case of road rage. He was directed by the Denver 911 operator to return to the scene of the incident where he was promptly shot dead.