By Joshua Brustein, Bloomberg Businessweek

Urban designers take note: If you want to create modern-day public squares that encourage strangers to cross paths, try offering outlets at which passers-by can plug in their phones.

AT&T has begun installing solar-powered phone-charging stations on locations around New York City. The thin towers are topped by solar panels and contain batteries to collect energy for nighttime use.

The company bought 25 charging stations priced around $8,000 each from Goal Zero, a solar-power company that worked with the design consultancy Pensa on the devices. AT&T began installing them a few weeks ago and was hoping to have them all up and working by this month.

In a pilot project last summer, Pensa said it was able to persuade people to congregate in a vacant plot of asphalt in Brooklyn’s Dumbo neighborhood. The designers believe that once you build these things, people will come.

“We’re looking to create something that complements its surroundings and invites people to hang out and recharge. We have also found that where people gather, opportunities develop for street vendors and retail, and neglected urban areas come alive,” says Marco Perry, co-founder of Pensa.

If you needed proof of our addiction to mobile communications, pay attention to the places where people can charge their smartphones.

Bartenders, for instance, will often agree to charge customers’ phones behind the bar – so long as they’ll sit there and buy drinks while they do so. A company called GoCharge has also installed charging stations in dozens of New York bars, paid for by advertisers.

At Brooklyn’s new Barclays Arena, crowds tether themselves to phone-charging stations in the concourse, watching the Nets play basketball on television screens while they’re paying to be there in person.

Last year, when the city faced widespread power failures in the wake of Hurricane Sandy, available outlets in ATM kiosks, coffee shops, and the odd adapters yoked to bicycle-powered generators helped sustain desperate crowds.

Creating mini-public spaces to feed popular demand for wireless communication became part of New York’s attempt to reinvent its pay phones.

Last year, after the city turned several pay phone stations into wireless hotspots, officials found that people who connected to the networks stayed in place for more than half an hour. The winning design in a contest the city ran earlier this year to reimagine pay phones included a Wi-Fi hotspot, while rival designs called for charging stations to be built-in.

The city renegotiates the franchises for its pay phones next fall. Don’t be surprised if, in the years to come, they’re the most popular places in town.