Imagine an advanced call center with 500 employees. The center can afford sophisticated technology such as geographic point identification of the call, bucketing multiple calls about the same incident, maybe even things like voice stress detection. And because of the size and geographic diversity, spikes in certain areas could easily be handled because they would make little impact. Even time zone diversification would cut costs, because traffic incidents from commuter times would be more evenly distributed.
Not to mention training. There are always incidents where, despite the good service of the vast majority of 911 workers, there are gross mistakes made in some cases that can be traced back to poor training. A large facility can develop excellent processes, training and electronic infrastructure to reduce these sorts of problems.
Or is this already done?