As NFL quarterbacks continue to go down with injuries, there's one guy who says he's ready for his shot -- COLIN KAEPERNICK.

The 33-year-old just sent ANOTHER message to GMs across the league -- saying he's BEEN READY to step in and compete for a job ... if there's a team with the cojones to pick up the phone and call.

"1,363 days of being denied employment," Kaepernick said on social media ... "Still putting in work with [Eric Reid].  
Still going hard 5 days a week.  #StillReady #StopRunning."

The message seems to be directed at the Bengals, who just lost #1 overall pick, Joe Burrow, to a knee injury over the weekend.

Kaepernick hasn't played a down in the NFL since the 2016 season.

Of course, Kap and Eric Reid both believe they're being blackballed for starting the now-famous kneeling demonstration during the national anthem.

High-profile critics including Donald Trump called for Kaepernick to be fired for kneeling -- despite support from people like Barack Obama, LeBron James and others.

As we've been reporting for years, Kaepernick has been training like a maniac -- and sources connected to the QB have been telling us repeatedly that he's been in game shape, ready to go at the drop of a hat.

Remember, it was Nov. 16, 2019, Kaepernick put his skills on display during a public workout -- and he looked pretty good.

So, will the Bengals, Cowboys, Jets or anyone else actually pick up the phone and make the call?