Depends on the implementation. Initially used ACH for settlement and now they are moving towards RTP. (https://www.earlywarning.com/press-release/early-warning-

Depends on the implementation. Initially used ACH for settlement and now they are moving towards RTP. (https://www.earlywarning.com/press-release/early-warning-services-clearing-house-enable-zelle-payments https://www.earlywarning.com/press-release/early-warning-ser...)