Citibank is enlisting the help of beacons to bring consumers into its Manhattan branches.

Citigroup Inc. recently deployed 32 beacons at each of the 10 branches piloting the technology, says Michael Anzola, vice president of mobile product management at Citibank. Beacons are small wireless transmitters that can sense a smartphone’s location via Bluetooth low energy.

One of the primary ways Citi is using the beacons is to allow its customers to enter the lobby of a branch after hours to access ATMs. The bank has placed a beacon near the entrance of each branch. In order to use the technology a consumer needs to have the Citibank mobile app, allow the app access to her location at all times, have Bluetooth turned on in the settings of her phone, bank in the New York, New Jersey, Connecticut tristate area and have an iPhone. About 450,000 consumers meet these requirements, says Deirdre Leahy, Citi’s public affairs officer.

Here’s how it works: When a consumer walks within 30 feet of a Citibank branch that has this technology, the beacon senses that the smartphone is nearby and it wakes up the Citibank app. The iPhone can be locked but it needs to be turned on for this to work. The beacon sends the consumer’s app an encrypted code that tells the app which bank branch the consumer is near. When the consumer is five feet away from the Citibank door she will receive a smartphone alert asking her if she would like to enter the branch. If she taps on the message, the Citi app will notify the bank’s backend system and it will unlock the bank’s door. If the smartphone is locked, the consumer will have to unlock it via her passcode or biometrics before the Citibank door is unlocked.

This whole process of receiving the alert, tapping it and entering the bank takes about three seconds, Anzola says. Compared to a traditional way of entering a bank lobby after hours of swiping a credit or debit card, the beacon option saves consumers at least 10 seconds, he says. And perhaps it saves even more time if it takes the consumer a long time to find her wallet in her purse, or if she doesn’t swipe the card in the correct direction the first time or if she is holding an umbrella or has to take off gloves, Anzola says.

Since a consumer may walk past a branch and have no intention of going in, Citibank programmed the notifications to automatically leave the consumers iPhone after 25 minutes. What’s also convenient about the technology is that the consumer does not need to wait for the app to load as the beacon automatically wakes it up, Anzola says. Also, the beacon is programmed to have a long range so a consumer only has to tap a button on her smartphone for it work and doesn’t have to hold her smartphone to the beacon, as with other similar technology such as Apple Pay.

Citibank is also using the beacons inside branches to send informational push notifications to its customers’ phones. The messages change depending on the amount of time the consumer is in the branch.

Citibank is using the new system to improve customer service and see if their customers like interacting with the bank in this way, Anzola says

“Going into this process and throughout it, we are looking for how to improve the experience for our customers and how to do that digitally,” Anzola says. The bank is also looking for ways to better reach and communicate with customers, he says.

Citibank is collecting feedback about the pilot via Citi employees asking customers their thoughts and in-app feedback. Citibank declined to share any metrics on how many of its clients are using the technology, only that customer feedback has been positive and exceeded the bank’s expectations, Anzola says.

“(With) financial services as a whole, there is a bit more hesitation,” Anzola says. “You don’t normally think about your bank as a place where you want to share your location information.”

Citi is working with mobile technology firm Gimbal Inc. for this pilot. The companies started talking about the beacon test in Q4 2014. The technology was piloted by employees for a month. Citibank made the technology available to its customers in the New York City tristate region in mid-March.

Gimbal provided the hardware for the beacons and the software development kit  that communicates with the beacons in the Citibank app. Citibank developed its app in-house and has a large team working on it, says Anzola without revealing specifics.

Anzola would not disclose the cost of the pilot, only that Citi is working to do it in an inexpensive and “scrappy” way, and working with a third-party vendor saved Citibank time and money over developing the technology themselves.

Brian Dunphy, Gimbal’s senior vice president of business development, says that the beacons themselves cost between $5-$25. The license for the SDK in the app that communicates with the beacons depends on the number of consumers that use the technology, and it is “a couple pennies per user a month,” Dunphy says.

Citibank is Gimbal’s first customer to use beacons to unlock doors in a large-scale level, Dunphy says.