What would you do if you were in danger? Call 999, we'd hope. But what if talking or making a noise could put you or those around you in even more danger? What would you do then?
You might not know it, but emergency services in the UK have a special procedure in place for this very situation. With the UK's terror threat level now "critical", it's important to know how to react when in danger.
Usually, if you call 999 and are silent, the operator will ask you to make a noise, such as a cough. But if you're unable to make a sound?
Police have admitted in the past that they don't automatically investigate every silent 999 (or 112) call, because there's a chance someone may have mis-dialled the number.
Earlier this year, they issued a reminder to the public that the 55 feature, known as Silent Solutions, exists – it is little known and could save women's lives.
“Please do not think that just because you dial 999 that police will attend," a police spokesperson told the Express & Echo.
“We totally understand that sometimes people are unable or too afraid to talk, however it must be clear that we will not routinely attend a silent 999 call.”
So, if you were as clueless about this as we were, why not help spread the word?