An emergency phone operator working for the Metropolitan Police has been sacked for mishandling 999 calls.
The 58-year-old PC, whose name has not been released, left the public in "potentially dangerous situations" by failing to follow up or obstructing requests for help, Scotland Yard said.
The force said he did not provide a police response to 141 cases, including rapes, domestic abuse and assaults.
However, it claimed nobody had been put at risk because of the failings.
The officer was based at Bow Central Command Centre in east London.
All of the cases took place over a 12-week period between May and July 2009, when the PC handled about 3,000 emergency calls.
He was negligent in almost 5% of these, the Independent Police Complaints Commission (IPCC) said.
His behaviour amounted to gross misconduct during 19 of the calls he took, it added.
The IPCC said one woman who called 999 to report her friend had been raped was told by the operator to take her to a local police station.
The correct response should have been to send a police car to the victim immediately.
The IPCC said on seven occasions the PC deliberately altered the final digit of the callers' telephone numbers, and later explained he was trying "to avoid conflict with his supervisors".
A woman who had reported a domestic assault complained after ringing 999 and finding the officer struggled to correctly spell her surname.
She told a friend who also worked at the centre in Bow, and managers were informed.
A subsequent Met investigation reviewed all of the calls dealt with by the officer.
Of the 19 gross misconduct cases, Scotland Yard said nine callers had immediately phoned another operator or subsequently went to a police station.
Six others received assistance from officers or other teams, such as social services, after their cases were reviewed.
The four remaining callers could not be contacted as they did not return messages or their numbers did not work.
But despite all of the failings, the force claimed nobody had been put at risk.
"It beggars belief that a police officer whose job was to help people in distress should have behaved in such an appalling and callous way," said Deborah Glass, the IPCC's commissioner in London.
"It is a matter of luck - and the persistence of those seeking help - that his actions do not appear to have resulted in serious harm to a member of the public."
The commissioner's findings were submitted to the Crown Prosecution Service, but it did not find enough evidence to press charges.
Scotland Yard Commander Peter Spindler said he wanted to reassure people that their calls were "taken seriously" and "high professional standards" were employed.
It was "only right that the misconduct panel took the allegations of failing to properly deal with emergency calls so seriously", he added.
He said: "It was a fellow call-handler who reported him, showing how shocked the vast majority of the hard-working and professional call-handlers were when they found that this one officer was not treating victims and witnesses with the appropriate concern, seriousness and high standards required."