Early on Wednesday, Simmons released a statement stating he wasn't going to join his Boomers teammates for the World Cup in China, instead using the time to prepare for the 76ers' coming NBA season.
Simmons -- who recently agreed to a five-year $US170 million ($A242.2m) contract extension with the 76ers, the richest contract signed by an Australian athlete -- said he was going to take part in the warm-up games, with the Boomers to take on Canada in Perth on August 16 and 17, and the USA in Melbourne on August 22 and 24.
He also said he wanted to represent Australia at the 2020 Tokyo Olympics.
"I wanted to let everyone know that after consulting with my representation, I've made the difficult decision to forego playing in the World Cup in China this summer," Simmons' statement read.
"I will still be heading back home to Australia to host my camps as well as train and play with the Boomers in the upcoming Exhibition Games. I'm really excited about the talent we have on the Boomers squad, especially moving closer to 2020 where I will be honored and humbled to represent my country on the world's biggest sporting stage at the Olympics in Tokyo.
"Ultimately, we decided it was best that I use the time in September to return to Philadelphia to acquaint myself with my new teammates and prepare for the upcoming NBA season.
"I appreciate Basketball Australia for their support and understanding. I look forward to working with my Boomers coaches and teammates over the next few weeks to start working towards our ultimate team goal of winning a medal at the Olympics."
Kellerman: Simmons isn't worth extension ... yet
Max Kellerman makes a case why Ben Simmons isn't worth the extension he got from the 76ers, but adds the team had to give it to him.