Ambulance watch: a day in the life of three emergency call centres
What happens after you dial 999 and ask for the ambulance service?
Do you get sent an ambulance to take you directly to hospital with the blue lights flashing, or are you asked to hang up and contact your GP instead?
Meet the individuals who have to make these decisions.
On Tuesday we are following the twitter streams of three emergency call centres - North West, West Midlands and East of England ambulance services - to find out.
Some of the calls taken today so far have are code red - meaning the patient is seriously ill and needs urgent attention. These should get an ambulance within eight minutes.
Others are amber or green - less urgent with a target response time of 19 minutes or an hour, respectively.
But some calls are inappropriate.
North West Ambulance Trust @NWAmbulance tweets: "just advised a patient with toothache to contact NHS 111 for further advice".
NHS 111 is the number to call when you need medical help fast - but it's not an emergency.
The next call North West Ambulance Trust picks up is from a man who has dialled 999 because he's drunk.
Meanwhile, East of England Ambulance Service has been called nine times today by a hoax caller. The caller's details have been passed on to the police.
Life or death
At West Midlands Ambulance Service, operators have been keeping a tally of where the calls received so far today have ended up.
Out of 1,490 emergency calls, just over half ended up being transported by ambulance to A&E.
Around 40% were visited by a paramedic but advised to remain at home, and 4% were given advice solely over the phone.
One of the calls answered by West Midlands was from a mother whose daughter had swallowed a felt-tip pen top. Her GP said to take her to hospital, but the mother has no car.
The call centre operator asked if the girl was choking. The mother answered: "No - but she has chest pain."
The advice from West Midlands is for the girl to be seen at hospital within the hour, but because her condition isn't life-threatening she can't be taken on blue-lights. The call is referred to the duty paramedic.
To follow the action live, follow #team999.
We'll bring you updates throughout the day on our Facebook page BBC News #nhswinter.