Phillips began training with the Australian women's national basketball team, the Opals, in 2005. She chose to participate in training camps and tours with the national team instead of joining the Connecticut Sun in the WNBA, who had drafted her in May of that year. She played several exhibition tournaments in China in July, and then helped the Opals qualify for the following year's World Championships in August with their victory in the Oceania Qualifying Series against the hosts New Zealand in August. Phillips's first major senior international tournament was the Commonwealth Games in March 2006, which were hosted by Melbourne and were including basketball for the first time. At home in Australia, the Opals won the gold medal in the women's basketball event, defeating New Zealand in the final by a lopsided margin. Phillips played an important role in the semifinal win against England. The following month, the national team hosted the Opals World Challenge in Canberra, where they defeated the United States women's national basketball team, who had not lost a game in seven years, for the first time since 1998.