Katherine Jackson had FULL ACCESS to a working phone during her stay in Arizona and could easily have called her grandkids whenever she wanted ... so says a rep for the resort.
A spokesperson for the Miraval Resort -- where Katherine stayed for nine days, beginning last week -- tells TMZ, Katherine stayed in a luxury villa that DEFINITELY contained a working phone.
For the record ... the villa also came with a full kitchen, a private patio, its own pool ... and its own butler.
And if full phone access wasn't enough -- Katherine also had FREE WI-FI.
Bottom line ... the Miraval Resort is adamant ... Katherine wasn't as cut off from the outside world as she previously claimed.
After yesterday's court hearing, Katherine's lawyer was asked why she wasn't allowed to use a phone to call her grandkids -- and her lawyer said he was told "the section of the facility she stayed at didn't allow phones of any kind. Or computers."
The Miraval rep insists ... that's just not true.