National police on Friday warned the public not to "test" the 10111 call centre, as operators went on strike again.
The service remained up and running and unnecessary or hoax calls to the emergency number placed strain on the queuing system, Major-General Sally de Beer said.
Contingency measures were already in place and had proved effective when the call centre operators went on strike last month, she said. Police officers were sent to take over from them.
"The strike action is regarded as a protected strike by SAPU-affiliated Public Service Act employees at 10111 call centres but 'no work, no pay' is applicable."
About 5 000 operators, represented by the South African Policing Union (SAPU), went on strike last month.
It was suspended four days later to allow the CCMA to help the parties find an amicable solution. SAPU said this proved fruitless.
Operators on Thursday again hung up their headsets. SAPU still wanted the operators' salaries to be increased by two notches, an estimated increase of R50 000 per annum.
Police management said in a statement said it would continue negotiations.
Operators are employed under the Public Service Act and are therefore not considered an essential service.