Verizon Wireless will offer subscribers Loopt's interoperable location-based, social-mapping service.

Loopt lets Verizon customers who opt in to be found by friends to show where they are located and what they are doing via detailed, interactive maps on their mobile phones. The service will be offered through Verizon's Get It Now mobile store for $3.99 per month on about two dozen phone models, a number that Verizon plans to increase.

"Loopt is about connecting people in a brand new way," said Jeffrey Nelson, spokesman for Verizon. "People who use these kinds of services find them very sticky, so it's a way for Verizon to keep customers for a long time."

Loopt helps friends connect on the go and navigate their social lives by orienting them to people, places and events.

With Loopt, Verizon Wireless subscribers can also choose to share location updates, geo-tagged photos and comments with friends in their mobile address book or via online social networks, communities and blogs.

"This mobile social networking service connects people in a way that they couldn't be connected before, providing a new benefit to Verizon Wireless subscribers," Mr. Nelson said. "Young people want elements of themselves to be visible to their friends, including their current location."

Loopt is also available to subscribers of Sprint, Boost Mobile, AlltelWireless, T-Mobile USA and AT&T Wireless.

"Until Loopt was available, people might never have thought this kind of thing was possible," Mr. Nelson said. "Ten years ago if you had asked people 'Do you want to watch TV on your cell phone?' they couldn't have imagined it. People can't imagine it until they try it."

Not surprisingly, Verizon is seeking to reach young people who are members of sites such as MySpace, Facebook, LinkedIn and other social networking venues.

"It's no shocker that the demographic this appeals to is young, equally male and female, multimedia-savvy, familiar with text messaging, mobile music and video clips," Mr. Nelson said.

Loopt offers privacy controls and security features for end users. Loopt is completely permission-based. Users share location information only with their known friends via private networks.

In addition, Loopt users can turn location-sharing on or off at any time on a friend-by-friend basis or for all friends at once.

Loopt is a stand-alone service, but other Verizon services eventually may be integrated into it.

For example, it could connect to mobile Web sites, and Verizon's VZ Navigator could be used by one friend to get directions to another friend's location.

"You'll be surprised to see how fun it is when it's up and running on your phone and you can see where your pals are at this very moment," Mr. Drake said.