iTransact is a payment gateway and merchant account provider. Its services allow Internet, bricks and clicks, and traditional brick and mortar merchants to accept payments via credit, debit, and gift cards, as well as electronic checks (and/or check conversion) with check guarantee.iTransact was founded in 1994 by the father and son team of G. Allen Sumsion and Mike Sumsion. Originally known as RediCheck, iTransact is one of the earliest providers of telephone-based check acceptance services.