Two phone companies recently added a global positioning feature to cell phones, which allows friends to locate each other with a push of a button, to the pleasure of protective parents but the chagrin of privacy advocates.

Boost Mobile, a division of Sprint Nextel Corp., launched a “location-based social mapping service” Nov. 20. The service, targeted at mobile phone users younger than 25, allows Boost Mobile users to share their location, status messages and photos with other users.

Boost Mobile offers a “pay-as-you-go” fee for the service, which is called “loopt.”

According to the release, Boost’s features are unique from other social location services because the system “automatically updates the location of everyone in a private network of Boost customers and displays that information directly on a map on the phone.”

Boost loopt also provides an alert to users via their cell phones when a friend in their network is near them.

“GPS-based services, such as loopt’s social mapping service, make sense in today’s mobile world,” Laura Evenson, a loopt spokeswoman from the SutherlandGold Group, said in an email on behalf of Mark Jacobstein, vice president of corporate development for loopt. “One of the most common text messages sent between friends is, ‘where are you?’ loopt answers that question and facilitates communication, allowing friends to meet in person.”

Evenson said the new GPS features are about a “deeper communication” because it is “bringing people together.”

According to Evenson, loopt has taken special measures to ensure the privacy of its users.

“On loopt, no one’s location is ever shared without their explicit permission,” Evenson said. “Loopt members can only see the location of their friends who have explicitly opted in to join the service. And loopt members and their friends can always turn off their location sharing at any time, for either all their friends or for individuals, depending on the circumstance.”

In an effort to encourage responsible behavior, users are not allowed to sign up for the service anonymously, she added.

Users can turn off the location sharing service through the phone, the Internet and through text messaging or through the loopt 800-number, according to Evenson’s email.

Boost Mobile is currently offering Boost loopt for free to customers who have java-enabled handsets until the end of the year. The company will start charging $2.99 per month for the service in 2007.

Customers can now download Boost loopt from their cell phones if they are java-enabled.

Helio, a new mobile brand also aimed at users in their teens and 20s, released a similar service that allows users to track their “buddies,” as well as a feature that lets users track their own locations when they are traveling. The service, to date, is available only for Samsung phones.

Helio’s new GPS features allow users to navigate local roads and highways to prevent them from getting lost while traveling, the press release said.

Courtney Carlisle, a Helio spokeswoman, said in an email that Helio’s Buddy Beacon feature allows users to share their locations with other “buddies” on a map.

“If you want a friend to turn on their Buddy Beacon, you can send a text message asking them to update their location,” Carlisle said. “Or you can call a nearby buddy, all directly from the application.”

Like loopt users, people who use Buddy Beacon can choose when they want their locations to be available to their friends. To protect users’ privacy, the system requires that users update their location status manually; it does not update automatically.

“First, members must explicitly authorize each Buddy by granting individual access to their Buddy List,” Carlisle said. “If you’re not on someone’s Buddy List, you cannot see their location.

Chris Schmandt, a spokesman for the Massachusetts Institute of Technology, said in an email that installing GPS features in cell phones has “many pros and cons and social implications of technology.”

According to a Dec. 3 Boston Globe article, Chris Galvin, the principal analyst at Forrester Research, estimated that there are “more than 100 million subscribers with GPS technology in their phones in the U.S., and that roughly 65 million more GPS handsets would be sold this year.”

Galvin said in the Globe article that he expects the younger generation will rely on GPS cell phones as they get older.

Arlyn Depagter, a senior in the College of Arts and Sciences said she would use the feature if she were bored in class, but she said GPS cell phone features could be helpful for parents with young children.

“But I don’t think it should be an option for everyone,” Depagter said. “It’s a bit of a violation of privacy.”

Nicholas Nikic, a senior in the College of Communication, agreed that GPS tracking could be beneficial to parents who have “wild teens or have a rocky relationship with their kids.” But he said that personally, he would not benefit from having the tracking features on his cell phone.

“In any case, there should be a feature that lets you turn the GPS on or off, or limit who can see your signal,” Nikic said. “In that way, you can have the benefits of this kind of technology – whatever they might be – in addition to the protection of privacy.”

Neil Marketkar, a Northeastern University student in his fourth year, said he does not see any use to the GPS feature.

“If they are your friends, and you want to know where they are, you could just call them and ask,” Marketkar said.