Technology allowing police and other authorities to identify the location of callers may become mandatory for all cellphones in New Zealand in a move to improve the 111 emergency calling system.But although the proposal could save lives, Telecom and the Privacy Commissioner have rung alarm bells.The mandatory global positioning system (GPS) idea was raised in a discussion paper reviewing the 111 system issued yesterday by Communications Minister Amy Adams.The review was prompted by 111 failures two years ago stemming from a fault in the Papatoetoe telephone exchange and from problems with Telecom\'s XT mobile network.In 2004, public confidence in the system was shaken when Auckland woman Iraena Asher disappeared from Piha. She had called police, but a taxi for her was sent to Paihia Rd (Onehunga) instead of Piha.The new proposal is to help find people who may be disoriented. The police report in 2004 said Ms Asher was unsure of the precise address.The review noted that although emergency service providers asked for the name and location of callers, it was important for them to have back-up location information automatically available in case the caller was under duress, badly injured, sick or did not know their specific location.That back-up information was available for calls made on landlines but they accounted for just 40 per cent of emergency calls.The location of callers using mobile phones was not independently available at present, the review said.\"This is a significant public safety issue since calls from mobile phones comprise the majority of 111 calls and are steadily increasing.\" The review noted some countries including the United States were making GPS technology - which locates the caller via satellite during an emergency call - mandatory.It noted the technology was costly but there was some potential to offset that through commercial applications such as advertising messages sent to shoppers\' phones as they passed particular shops.Mark Watts of Telecom said the idea \"raises issues of cost, technology compatibility and privacy and probably a whole lot of other issues\".A spokeswoman for Privacy Commissioner Marie Shroff said the commission had not seen the review but \"would consider whether the public interest outweighed privacy issues for something like this\".