In US, 911 is the number to call in case of emergency.
If 911 calls placed from landlines are easily traceable, wireless calls do not reveal location information. To avoid delays, wireless carriers will have to provide call centers with:
– the caller’s geographic coordinates,
– his mobile phone callback numbers,
– the location of the towers or antennas receiving their calls.
The PDF enclosed demonstrates how it will work.
From Technology Review.