The Atlanta Hawks have begun listening to trade pitches for All-Star forward Paul Millsap in recent days, according to league sources.

S‎ources told ESPN.com that the Hawks, fearful of losing Millsap in free agency without compensation in the summer, are not openly shopping him but are taking calls on the 31-year-old and other pending free agents, notably sharpshooter Kyle Korver and swingman Thabo Sefolosha.

Although the Hawks managed to sign Dwight Howard in free agency last summer to fill a frontcourt void, they were stung by the free-agent departure of Al Horford in that Horford, in the words of one source with knowledge of the team's thinking, got away "for nothing."

The feeling within the organization now, sources said, is that it's best to gauge the trade market for Millsap, Korver and Sefolosha between now and the Feb. 23 trade deadline to guard against a repeat scenario.

The Hawks slumped to 48-34 last season and took a 17-16 record into 2017 after an offseason in which Teague was traded to Indiana before Horford's free-agent defection to Boston.

The Atlanta Hawks, fearful of losing Paul Millsap in free agency in the summer without compensation, have begun to listen to trade pitches for their All-Star forward. Photo by Gary Dineen/NBAE via Getty Images

ESPN's Chris Haynes reported Sunday that Millsap has already‎‎ decided to opt out of the final year of his Atlanta contract, valued at $21.5 million in 2017-18.

Some rival teams have expressed concern to ESPN.com that the Hawks want so much in return for Millsap that it makes a trade unlikely before the deadline. But it should be noted that Atlanta got far down the road in trade talks with the Denver Nuggets last summer, before the Hawks ultimately decided it was best to keep the versatile forward, who has ranked as one of the league's biggest matchup problems throughout his time in both Utah and Atlanta.

The Toronto Raptors, sources say, are another team that has expressed interest in Millsap in the past.

Millsap, who turns 32 two weeks before the trade deadline in February, entered Sunday night's home date with San Antonio averaging 17.4 points and 8.0 rebounds. He has earned Eastern Conference All-Star berths in each of his three seasons since joining the Hawks in free agency before the 2013-14 campaign, and he earned All-Defensive Second Team honors for the first time last season.