Kendra Duggar isn't sugarcoating the reality of her husband, Joseph, being behind bars on child molestation charges ... telling him his family is "disappointed" during a jail call obtained by TMZ.

You can hear part of the "19 Kids and Counting" star's chat from last Thursday -- the couple is talking about Joseph's famous family when she says everyone still loves him even though they're not happy about his current situation. And Joe seems understanding of their disappointment ... noting he also feels their love.

Kendra goes on to encourage him to take everything one day at a time ... and he happily obliges.

Things seemed pretty upbeat between the pair, considering their respective arrests just 2 weeks ago. We told you all about it -- Joseph was booked into jail in Tontitown, Arkansas, for lewd and lascivious behavior involving unlawful sexual activity with a minor stemming from an incident in 2020.

Then, days later, on March 20, he and Kendra were both hit with child endangerment and false imprisonment charges resulting from a separate investigation. Kendra was booked that evening and released hours later on a $1,470 bond.

Joseph remained behind bars and was transferred to the Bay County Sheriff's Office in Florida on Tuesday morning, where he will face child sex abuse allegations made against him.

As you know, Joseph's arrest comes 5 years after Josh Duggar was arrested and then convicted on child pornography charges. He is currently serving a nearly 13-year sentence. Josh has stood in solidarity with his younger brother.