Opportunity missed in GSM?
Looking at the comments above it does seem that an opportunity has been missed in GSM for an emergency call type. By contrast, modern VHF ship radios have an integrated Digital Selective Calling feature with specific emergency call abilities. Press the big red button on the set and a digital Mayday message gets sent along with the unique MMSI number of the vessel and the GPS coordinates (as long as the radio is connected to a working GPS receiver). It's a broadcast message so everyone within range gets alerted with the relevant details - in general you hope that the Coastguard get it but if they don't, the fallback should be to other vessels within range.
It may be too late now, but if that had been included in the GSM specification, most phones could have had an emergency call facility which one would imagine would also request the cells to do their best to provide location information - either range from the base station, or, if in range of more than one, triangulation.