 Later that year, McCullum was selected as part of the 30-man preliminary squad for the Champions Trophy alongside fellow Otago teammates Warren McSkimming and Bradley Scott but ultimately missed out on the final squad.McCullum is building a reputation as a travelling Twenty 20 player, having played in Twenty 20 tournaments since 2010 for Lancashire, Pune Warriors India, Sunrisers Hyderabad, Sydney Sixers and Glamorgan as well as still turning out for his native side Otago.He made his Twenty20 International debut for New Zealand against South Africa on 19 September 2007 at the Twenty20 World Cup in South Africa.