WAILUKU, Maui — Enhanced 911 service that can pinpoint the location of wireless telephone users who need help is now available on Maui.

The service is expected to be particularly useful in cases where callers are lost while hiking or in the ocean, or are unable to speak to 911 dispatchers because of an injury or medical emergency. It also may come in handy for tourists needing assistance who don't know where they are in the Islands.

Maui is the first county in the state to implement the service, and it will be months before the enhanced 911 system is up and running on O'ahu, Kaua'i and the Big Island, said Roy Irei, chairman of the state's Wireless Enhanced 911 Board. County officials in Honolulu, Kaua'i and the Big Island who are familiar with the program were not available yesterday to comment.

Maui was able to lead the way because it was already far ahead in creating mapping systems and other preparations, said Mayor Alan Arakawa during a ceremony yesterday at the Maui Police Department headquarters in Wailuku.

But even on Maui, the service is available only to Nextel Partners subscribers. Nextel accounts for about an eighth of the 800,000 cell phone users in the state, said Nextel public relations manager Courtney Wells. Other wireless providers are working to get their systems in order to join the enhanced 911 program. Irei, who works for T-Mobile, said he expects his company will be ready in about three months.

Radio dispatchers at Hawai'i's police departments already are able to identify the addresses and locations of those who dial 911 on a traditional land line. But officials said half of 911 calls are made by cell phone users.

Nextel phones are equipped with assisted global positioning system technology that uses orbiting satellites to find a caller's location to within several hundred feet, and sometimes to within inches.

Triangulation, in which a location is determined by a network of cellular receiving towers, is an alternate technology also used for the enhanced 911 system.

Wells said Nextel phones purchased within the last year and a half likely have the built-in GPS systems. This can be confirmed by checking the menu or calling the service provider.

During yesterday's demonstration, it took only seconds for Maui police radio dispatchers, using detailed maps and aerial photos, to zero in on the location of wireless callers. The system can provide information on the address of the location and the property owner, with other maps showing whether callers stranded at sea fall within the range of county lifeguards' watercraft, fire department rescue boats, or Coast Guard crews.

All wireless phone users in Hawai'i have been paying a 66-cent monthly surcharge since July 2004 to support the enhanced 911 system. The fund, administered by the Wireless Enhanced 911 Board, is expected to raise almost $6 million annually, earmarked exclusively to upgrade wireless carrier locations and 911 call centers.

The Maui Police Department got additional money yesterday to reimburse its enhanced 911 costs in the form of a $199,000 check from Nextel.

The Federal Communications Commission in 1997 passed regulations requiring the wireless telephone industry to convert to enhanced systems in two phases. The first phase, completed in June 2000, allowed emergency personnel to determine a caller's phone number and the location of the tower receiving the call. The second phase requires the companies to come up with their own plans for implementing automatic location identification systems, a much more complicated and costly undertaking.

To support the effort, the state Legislature last year approved the 66-cent fee.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.