Kallum rejoined the Nailers in July 2017 after making a few appearances at Christchurch Meadow in 2010, immediately following his release as a trainee by Derby County. Following his departure from Pride Park, Kallum spent a brief period at Alfreton Town before embarking on a spell with Exeter City, after a successful trial. He departed the south west in 2011 and then played for Buxton and Eastwood Town on his return to the East Midlands. Kallum has also had spells with Gresley, Long Eaton United and Carlton Town. He can reliably play in a number of defensive positions and also in the anchor role in midfield.