The Sidney MT Police Department is located at 110 Second Ave NW, call 406-433-2919 to find out about new arrests or outstanding warrants. This is a police jail for housing inmates immediately after their arrest. Local police departments are not built for long-term inmate holding, they are for very short-term stays because there are not enough cells. There are no visits, commissary or phone accounts available to the offenders.
If they are to remain incarcerated, it will be most likely to the Richland County Sheriff's nearby facility.