Born in Whitehaven,[3] Phillips started his career as an amateur playing for Seaton.
He was named Gillette National Youth League player of the year in 2010.
He is eligible to play for Scotland through his grandparents, and was called up to their squad for the 2013 Rugby League World Cup following the withdrawal of Gareth Moore due to injury.
[6] In October 2014, Callum was again selected for Scotland but this time he managed to escape injury and play in the 2014 European Cup tournament.
He made his International début in the tournament's opening game against Wales.