Tickets went on General Sale to Iron supporters on Wednesday morning.
United announced last week that supporters will have to sit in the seat specified on their ticket for the Caring Cup Second Round clash.
The Iron are selling to seats to make sure they can optimise Glanford Park to its full capacity for the match.
Birmingham City have asked for 1,000 tickets initially, but they can have the additional 678 tickets in the Caparo Stand if required.