The Scottish side face Leinster in their final Magners League game of the regular season and Callam - who endured a year on the sidelines - knows now is the time to deliver.
Even in Edinburgh's disappointing 37-25 defeat against Ulster last Sunday Callam still managed to enhance his reputation - and now the back-rower intends to further impress.
"I'm enjoying being back playing. Obviously there are things I can still work on," he said.
"I'm looking ahead to a good pre-season and hopefully I can start with a clean slate.
"There are a few things I still want to address with agility, speed and power. But personally I'm delighted to be back playing.
"For the team, I'm hugely disappointed having positioned ourselves for a high finish in the league. The last three weekends have been a massive disappointment.
"I've been a part of Edinburgh for a long time and they have stuck with me right through my injury.
"Obviously I want to repay the faith they've had in me."