Kim Zolciak Calls 911 on Kroy Biermann Over Alleged Kidnapping Accusation

Kim Zolciak called the cops on her estranged husband, Kroy Biermann, earlier this month -- and it was all because he allegedly accused Kim's friend of kidnapping their young son.

TMZ obtained audio from the 911 call Kim placed on June 16 in Alpharetta, GA. In her chat with the dispatcher, Kim says she's stressed out about her husband flipping out ... claiming he accused her friend of trying to kidnap their son.

The backstory is a little murky ... but essentially, KZ explains that she'd signed off on her girlfriend to take her son on a playdate. However, based on Kim's description, it sounds like when Kroy caught wind of this, he lost it and threatened to file a kidnapping report against the woman who was picking up their son.

Kim says this caused not only her friend to freak out, but also left Kim's son in tears ... and Kim tells the dispatcher she's going to pick up her son. It's a strange call -- obviously, it doesn't seem to be an emergency -- something Kim acknowledges herself.

BTW ... Kim also accuses Kroy of stealing her bag, which she says is full of divorce docs.

Based on police records, it appears nothing came of this at the time. Kim ends the call by telling the operator she'd call them back if she needs further assistance -- but, on its face, she seems to have just wanted to put this on the cops' radar ... which is exactly how the police noted it in their write-up. They didn't follow up on this address in the aftermath.

Now, when it comes to Kroy's side of things ... sources tell us this was just a case of bad communication. We're told Kroy had no idea their son, KJ, had gotten the green light to go to a rodeo with his friend/their mom. Our sources tell us Kroy's deeply distrustful of the woman who took KJ -- for reasons unexplained -- which is why he was on edge.

We're told when Kroy learned KJ was under the supervision of this woman -- he called her up, but apparently felt like he wasn't getting his point across. At one point, our sources say Kroy demanded she brings KJ back ... she allegedly hung up on him -- which is what led to him threatening to file kidnapping charges over it. He never did, though.