NEW YORK - Here's a cool use for a phone that has both cellular broadband and Wi-Fi: Turn it into a mobile Wi-Fi hotspot so your friends can surf the Internet on their laptops.

A couple startups have created and made available software like this in the last year. But a more established software maker said Wednesday that it has created a package for carriers to offer their customers.

TapRoot Systems Inc. of Research Triangle Park, N.C., said it was talking with carriers about providing their customers with the software, which would let up to five Wi-Fi users connect to a phone.

A possible free trial version would let only one Wi-Fi user connect to the phone at a time.

The software works on phones with Windows Mobile or Symbian S60 software. Windows phones are common in the U.S., while Symbian is championed by Nokia Corp. and more common in Europe. There already is an independent program called WMWifirouter that turns Windows phones into hotspots, and there's one called JoikuSpot for Nokia phones.

Capacity is limited on third-generation cellular broadband networks, and carriers are somewhat restrictive of the applications they allow, for fear their networks will be overwhelmed.

TapRoot's system attempts to assuage that fear by letting carriers control access through a server, said Chief Executive Bob Bicksler. The carriers could then charge extra for the service, he said.

Not many phones have both 3G and Wi-Fi. U.S. carriers have in some cases removed or disabled Wi-Fi antennas for the U.S. launches of some phones by overseas manufacturers, apparently because they fear customers would be less likely to pay for 3G. However, combined Wi-Fi and 3G phones are becoming more common.

Bicksler mentioned AT&T Inc.'s Tilt and 8525 models and Sprint Nextel Corp.'s Mogul by HTC as phones that would work as mobile hotspots.

Another way of using a 3G network to create a Wi-Fi hotspot is to buy a Wi-Fi router that accepts a cellular broadband card. Cisco Systems Inc. makes such a router for the Sprint network.