ClearXchange has racked up an impressive series of wins in recent months, bringing several major banks live on its realtime payments network. But this week it may have scored its biggest win of all — signing longtime holdout Citigroup.

ClearXchange’s client roster already includes the nation’s largest banks: JPMorgan Chase, Bank of America, Wells Fargo, U.S. Bank, Capital One, and smaller players. The addition of Citi means it now has virtually every large consumer bank on its network.

With same-day ACH and a ubiquitous realtime interbank P2P network, realtime payments are fast becoming a reality for the U.S.

Citi, in some sense, represents the completion of a challenge for ClearXchange (which is owned by Early Warning, and will be renamed Zelle for some reason at Money20/20 in October.) It’s got the big players, and is unanimously the person-to-person payment network of choice for large banks in the U.S.

It is often said that ClearXchange is taking on Venmo, or more broadly, PayPal, which has just completed deals with Mastercard and Visa. The two networks, however, also joined clearXchange this summer, so rather than battle lines being drawn between the banks and fintech, realtime payments is turning into a web of connected networks. (Banks, after all, are the largest investors in fintech.)

“The addition of Citi represents a significant milestone in Early Warning’s goal to expand the clearXchange network to include all financial institutions nationwide,” said Paul Finch, Early Warning’s CEO. “Early Warning is pleased to partner with Citi to provide its customers access to realtime P2P payments across the clearXchange network.”

Citi and clearXchange have broader ambitions for the service, as well. “ClearXchange functionality will be made available for Citi customers online and via mobile in early 2017,” Barry Rodrigues, global head of digital payments at Citi, told Bank Innovation. “While the initial use case will focus on P2P, we are engaged with the clearXchange team on ways to leverage the network to offer new and enhanced value propositions to our customers.”

Fiserv’s Popmoney, which signed a partnership deal with clearXchange this summer, was previously Citi’s sole P2P payments provider. Citi will not abandon Popmoney, but rather will continue to offer it alongside clearXchange, according to Fiserv.

The Popmoney linkup, when it occurs, will add thousands of smaller FIs to the network. A patchwork network of independent players was long predicted to be the way realtime would work out in the U.S., as opposed to a new, unified system created by the Fed or similar entity.

Consumers, and perhaps particularly small businesses, will take it.