Middlesex County Sheriff Department
The Middlesex Sheriff's Office provides a secure, safe and humane environment for both staff and offenders. Our commitment to public safety is to improve the quality of life in the community through public awareness, reintegration and by exercising our core beliefs of professionalism, respect, fairness and integrity. Public Safety is our Public Service, established in 1643, Middlesex is one of the oldest sheriff's offices in the United States. Although the Middlesex Sheriff's Office is statutorily entrusted with full law enforcement capacities within the jurisdiction of Middlesex County, the primary responsibility is the care, custody and control of inmates and detainees within Middlesex County. This function is carried out at the Cambridge Jail and the Billerica House of Correction. Additionally, the Middlesex Sheriff's Office is responsible for the Sheriff's Office of Civil Process and the Cambridge and Lowell Community Counseling.
The 800 Megahertz frequencies have been re-banded.
| Frequency | Type | Tone | Usage | Confirmation/Re-Confirmations |
| 851.5500 | R | 131.8 | Billerica House of Correction | 2012.12.12 N1BHH |
| 851.7500 | R | 131.8 | Cambridge Jail | 2012.12.12 N1BHH |
| 45.9400 | S | D023 | Billerica Transport | |
| 46.0200 | S | D023 | Billerica Transport | |
| MSP Trunk | T | TG 37040 | Statewide Correctional Facility Transportation | 2011.05.19 |
