Regions Financial Corp., a Birmingham, Ala.-based bank with a footprint in 16 states, announced yesterday that it would be implementing Fiserv’s CheckFree RXP bill pay service. The service will enhance the bank’s current bill pay capabilities, powered by Fiserv’s Corillion system.

“CheckFree RXP will offer our customers a simple, integrated payment solution and strengthen our position as a central source for consumers’ financial needs,” said Christopher Cox, executive vice president and head of eBusiness at Regions, in a bank press release.

The new service will allow users to receive bills from more than 500 billers directly within the platform itself. The system is not yet implemented and no timeframe is set, according to the bank.

Online bill pay is thought to be one of the “stickiest” services a bank can offer — in other words, it’s painful to switch your billpay profile between banks.

Regions has assets in excess of $120 billion, so this is a big win for Fiserv.

Regions also employs Fiserv’s Popmoney peer-to-peer money movement service.