IT is, literally, a lifeline. It is the telephone number we first teach our children and the one we hope never to use: 999. The knowledge that the emergency services are only three digits away is a huge comfort. In times of desperate trouble we know we can summon help in seconds.

But that guarantee has been undermined today. While there are no problems reaching the fire or ambulance service, two York residents were stunned when they rang 999, were put through to the police by the operator, but then received no answer.

When youths threatened to attack her staff, caf owner Val Ross knew what to do. She dialled 999 and asked for the police. The phone rang and rang, but was never picked up.

Philip Fowler was also left hanging on the line while trying to report a gang of youths in the act of vandalising a garage.

The experience has shaken their faith in the police. But the lack of a response did not surprise the youths who threatened Val Ross's staff. They mocked her attempts to get help, telling her the police "would probably arrive next week".

These system failures did not result in anyone being hurt. But that was just good fortune.

What if the unanswered caller had been a lone woman woken by the sound of an intruder? It is easy to imagine how terrifying it would be for such a desperate plea for help to be met by an endless ringing tone.

Police resources are stretched. And the number of 999 calls has increased dramatically. Many are not emergencies, and Home Secretary David Blunkett is backing a national non-emergency police contact number to take pressure off the 999 system.

Nevertheless, there are no excuses for North Yorkshire police's failure to answer 999 calls. The force must fix the problem before public confidence in this vital service is further undermined.

Updated: 10:19 Wednesday, July 31, 2002