If you phone 999 and you can’t speak (for example choking, a heart attack, an intruder, domestic violence etc), there is a solution which will help you.
The operator will ask you which service you require. If you don't reply, they will ask you to cough, or tap the handset. You will then be given the option to press 55.
This tells the operator that you need help but are unable to speak. They will try to work out where you are and dispatch police to your location.
If you don't respond to any of the operator's questions, they will assume that you called 999 by accident and they will end the call.