Windhorst noted the unnamed team "has a lot of interest" in the three-time All-Star.
There are "four or five" teams that remain in the hunt for Simmons, according to Windhorst.
Simmons has reportedly told team officials he no longer wants to be part of the 76ers and he does not plan to report to training camp, according to Keith Pompey of the Philadelphia Inquirer.
There have been no shortage of links between the 76ers and teams around the NBA regarding a deal for Simmons this offseason.
The Sacramento Kings reportedly discussed a deal for the guard, per Sam Amick of The Athletic, but they believe the price tag is currently too high. The Golden State Warriors have also been involved in talks, but the two sides have yet to find a realistic offer, per Anthony Slater of The Athletic.
The Cleveland Cavaliers are another possibility, with NBA reporter Marc Stein saying the team "continues to keep its hat in the ring."
Philadelphia still has a high asking price for Simmons, even though his value is at its lowest. The 25-year-old earned his third straight All-Star selection this past year, but his 14.3 points, 7.2 rebounds and 6.9 assists per game were all career lows.
Simmons' lack of aggressiveness on offense was glaringly apparent during the postseason, as he averaged only 9.9 points per game in the Sixers' second-round loss to the Atlanta Hawks.
Even with his elite defensive ability and knack for filling up the box score, there is a lot of risk in acquiring a player who's owed at least $30 million in each of the next four seasons.