The Alton NH Police Department is located at 15 Depot St
PO Box 240, call 603-875-0757 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 Belknap County Sheriff's nearby facility.