Villarreal loanee Xavi Quintiila looks to be Daniel Farke’s first choice at left-back so the 20-year-old has returned to his former club to ensure his development doesn’t stall.
McCallum was a major part of Coventry winning promotion from League One under Mark Robins last season, sealing a permanent switch to Norwich in January in a deal reportedly worth up to £3.5million but remaining on loan initially.
He featured regularly during pre-season and played 86 minutes of the 3-1 loss at Luton in the first round of the League Cup but has not been on the bench for either of City’s league matches so far.
The loan allows him to play Championship football this season, with the Sky Blues losing 2-1 at Bristol City on the opening weekend but winning 3-2 at home against QPR on Friday
McCallum played for the Norwich U23s on Monday, playing all of a 3-0 home win over Reading in Premier League Two.
The former Gillingham trainee signed a long-term contract through until 2024 when he joined.
The decision may come as a surprise to City supporters, after seeing Jamal Lewis sold to Newcastle for an initial £15m recently, leaving Quintilla as the only recognised senior left-back - whose deal is set to be made permanent if promotion can be achieved.
However, Max Aarons and Ben Godfrey have both played on the left previously, while summer signings Bali Mumba and Gibson are also understood to be seen as options and Marco Stiepermann has also played at left-back under Farke previously.
In the academy ranks, Belgium Under-19 international Rob Nizet would appear to be the chief option, with Caleb Richards loaned out to National League North side Kidderminster Harriers.