Google quietly ran a test of new technology to make it easier for 911 operators to locate cellphone callers, and 911 centers that participated said the results were promising.

The nation’s existing 911 system, which turns 50 this month, has struggled with the explosion of cellphones. The vast majority of 911 calls these days are made using a cellphone, but the location of the caller is hard to pinpoint. Federal regulators estimate shaving a minute off response times could save as many 10,000 lives each year.

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