If you're in danger, call 999 and try to speak to to the operator if you can, even by whispering. You may also be asked to cough or tap the keys on your phone to answer questions. 

Call 999 from a mobile

If you don't speak or answer questions, press 55 when prompted and your call will be transferred to the police. 

Pressing 55 only works on mobiles and doesn't allow the police to track your location.

If you don't press 55 your call will be ended.

Call 999 from a landline

If you don't speak or answer questions and the operator can only hear background noise, they'll transfer your call to the police. 

If you replace the handset, the landline may remain connected for 45 seconds in case you pick it up again.

Calling 999 from a landline automatically gives the police information about your location.