You'll really pee the ambulance service off if you dial 999 when someone is definitely dead!
When I worked on the railways, fatalities on the track were fairly common. (Roughly one person per day dies on Britain's railway lines). Railway rules state that (whatever the emergency) the driver must immediately speak to the signaller, not to the 'emergency services'. If the driver reported a possible injury, the signaller would call an ambulance but if the report was (as usual) of a definite fatality, the signaller would advise British Transport Police (because all fatal incidents had to be regarded as possible crime scenes) and get his bosses (at Network Rail) to contact the on-call funeral director for that area. There would have been possible dismissals if someone called an ambulance when it was clearly pointless to do so!
If someone is blue, rigid and cold, call a funeral director and leave them to get death certified. (When I did my first aid training, I was told - both by trained nurses and qualified doctors - that the 'unofficial' rule is that you should never commence resuscitating anyone who has ceased breathing for more than four minutes. Nobody seems to want to commit that 'rule' to print but I know that it's commonly used in the medical profession).
Chris