One hundred officers have been moved from dealing with emergencies to being on the beat to improve policing in south London, Scotland Yard has said.
Local policing teams in the borough of Lambeth will deal with less urgent matters, while a smaller emergency response unit will handle 999 calls.
The pilot scheme will be replicated in Brent and Harrow from April.
The Metropolitan Police (Met) promised emergency calls would still be given priority under the new arrangement.
Calls from the public which were classed as needing "immediate" or "significant" action would be passed to the new, smaller swift response team, it added.