"I wasn't expecting the call from Freddy at all," Sims told NRL.com.
"My daughter actually had my phone at the time and it had died while she was using it.
"She hadn't told me it was dead, as kids do, and it wasn't until about 8.30am I'd realised my phone had been off.
"So I threw it on charge and at about 9am, I checked it again and I had a couple of missed calls and messages - before word started to filter through with the good news.
"It was one of those moments where you pinch yourself."
Like the majority of Sims' teammates, coach Freddy has allocated a specific role for him in the side.
"That job is to make the ball-players get the footy out of their hands early, by putting legal pressure on them.
"It's no easy task, as they've got some of the best playmakers in the game, but I'm ready to give it a go.
As zeroed in as he is on the clash at Townsville, Sims isn't taking this chance for granted, as he wants to help the Blues regain the series trophy.
"This is definitely the pinnacle of my playing career and one of the proudest moments I've ever had," he said.
"But I know, if I make a mistake, I could be out the door.
"Everything I do needs to be calculated, done the right way and done in a way that's beneficial to the team because Origin is such a team sport and you can't do things one-out.