TMZ Sports has obtained the Lawrence Phillips' 911 call -- in which a prison staffer tells the operator to send help because the ex-NFL star "has attempted suicide right now."
During the call, the staffer says he's in the dark about Lawrence's condition or how he tried to take his own life ... but says he was instructed by other Kern Valley State Prison staffers to call for an ambulance asap.
By the way, officials say the call came in to 911 at 12:14 AM -- 9 MINUTES after prison officials say they found Phillips unresponsive in his cell.
As we previously reported, Phillips' next of kin -- along with his biological mother and his lawyer -- do NOT believe Lawrence committed suicide ... and are demanding an investigation into the death.
Prison officials say Phillips was found unresponsive in his cell early Wednesday morning and was pronounced dead 90 minutes later after he was transported to a nearby hospital.