More than 4 million people have enrolled in Zelle, the mobile phone-based payment network backed by many of the nation’s largest banks, since its launch in June.

That is according to Melissa Lowry, a vice president at Early Warning Services, the bank-owned company that runs Zelle.

Zelle was designed to operate both as a feature within mobile banking apps and as a stand-alone app that can be used by consumers who do not have deposit accounts at participating banks.

So far, 11 banks have launched the person-to-person payment service inside their own mobile apps: Bank of America, Capital One Bank, JPMorgan Chase, Citibank, Fifth Third Bank, 1st Bank, PNC Bank, TD Bank, U.S. Bank, USAA and Wells Fargo.

The Zelle stand-alone apps for iPhones and Android phones will be released on Tuesday, Lowry said.

Zelle is the big banks’ answer to Venmo, the PayPal Holdings-owned mobile app that has gained popularity among members of the millennial generation. It builds on an earlier service, also owned by banks, which suffered from a lack of consistent branding and a failure to provide a consistent user experience.

Lowry said that the average payment on Zelle is $330, which is in line with what participating banks previously saw on the earlier version of the network.

“We see a lot of rent payments come through, and other higher-value things,” she said. “We think that’s in large part due to that trusted relationship that people have with their banks.”

Zelle is targeting U.S. adults between the ages of 18 and 54 who already rely heavily on their mobile phones, a category that is said to encompass 103 million consumers.

Corrected September 18, 2017 at 6:50PM: An earlier version of this article stated erroneously that SunTrust Banks has launched Zelle inside of its mobile app. SunTrust is partnering with Zelle, but has yet to launch the service, a spokesman for the payment network said on Sept. 18.