Simplex 2975-9053 Firefighter Phone Backbox

The Simplex 2975-9053 is a red firefighter telephone backbox designed for Simplex remote emergency telephone equipment. It provides the enclosure required for mounting compatible firefighter telephone assemblies in fire alarm and emergency communication systems. Official Simplex/Johnson Controls documentation identifies it as a separately ordered backbox used with compatible 2084 Series firefighter telephone assemblies.

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Product Functions

• Provides a backbox for firefighter emergency telephone assemblies
• Supports Simplex 2084 Series firefighter telephone equipment
• Provides mechanical protection for the telephone assembly
• Supports permanent wall installation
• Suitable for surface or flush telephone configurations when used with the appropriate door/assembly
• Provides space for telephone equipment and associated field wiring
• Can be installed during rough-in before the complete telephone assembly
• Designed as part of a dedicated fire alarm emergency communication system
• Finished in red for fire/life-safety identification

Simplex specifically describes the 2975-9053 as a red backbox available for pre-installation.

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Firefighter Telephone Application

The 2975-9053 forms part of a firefighter emergency telephone system.

These systems provide dedicated two-way communications between remote firefighter telephone locations and a master firefighter telephone, typically located at the fire command center or fire alarm control equipment.

The 2975-9053 itself contains no telephone electronics. Its function is to house and support the compatible remote telephone assembly.

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2084 Series Compatibility

Official Simplex documentation lists the 2975-9053 under:

Remote Emergency Telephone Equipment – 2084 Series Firefighter Telephones.

Simplex documentation identifies it for use with various firefighter phone assemblies, including models associated with the:

• 4590-B
• 4590-BX
• 4590-C
• 4590-CX

families.

A current distributor also identifies the product as the “Box, Phone 4590-B-C-D.”

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Pre-Installation

An important feature of the 2975-9053 is that the backbox can be pre-installed.

This allows the enclosure and associated conduit/wiring infrastructure to be installed during building construction before the finished firefighter telephone assembly is fitted.

Simplex’s 2022 documentation explicitly describes:

2975-9053 — Red Back Box available for pre-installation.

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Physical Specifications

Official Simplex documentation specifies:

Height: 13 in / 330 mm
Width: approximately 9 9/16 in / 243 mm
Depth: 3 1/2 in / 89 mm
Color: Red
Product Type: Firefighter Phone Backbox.

An earlier Simplex document renders the width as 9 11/16 inches, while retaining the same metric dimension of 243 mm. The current 2022 documentation gives 9 9/16 inches, so 330 × 243 × 89 mm is the clearest manufacturer dimension to use.

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Backbox with Knockouts

The 2975-9053 is distinguished from another Simplex backbox:

2975-9053: Red backbox

2975-9313C: Red backbox without knockouts.

This distinction is important when specifying replacement or new-installation equipment.

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Compatible Doors

For applicable Canadian 2084 Series configurations, Simplex lists compatible doors including:

2084-9103-C: Red surface door

2084-9104-C: Red flush door

2084-9105-C: Stainless-steel flush door.

The appropriate door is selected according to the desired mounting arrangement and project requirements.

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Compatible Phone Assemblies

Simplex documentation lists telephone assemblies such as:

2084-9106-C: Red phone assembly with armored cable

2084-9107-C: Red phone assembly with retractable cable.

The 2975-9053 is the backbox only. Telephone assemblies, doors, and other required components are selected separately.

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Electrical Specifications

The 2975-9053 is a mechanical enclosure, not an active electrical device.

Therefore, the backbox itself has no:

• Operating voltage
• Standby current
• Alarm current
• Address
• Relay rating
• SLC requirement
• Audio rating

Electrical specifications are determined by the firefighter telephone equipment installed inside the backbox.

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Firefighter Telephone Wiring

Although the 2975-9053 itself has no electrical operating requirements, the associated firefighter telephone system uses dedicated communication wiring.

Simplex firefighter telephone documentation describes typical operation using a dedicated two-wire circuit, commonly with twisted shielded pair wiring to reduce electrical noise.

Field wiring and conduit are routed into the backbox according to the specific telephone assembly and approved system design.

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Installation Information

Typical installation includes:

• Selecting the firefighter telephone location
• Confirming mounting requirements
• Positioning the 2975-9053 backbox
• Securing the backbox to the building structure
• Routing required conduit to the enclosure
• Routing firefighter telephone field wiring
• Installing the compatible phone assembly
• Installing the appropriate surface or flush door
• Securing all components
• Connecting telephone field wiring
• Testing communication with the master firefighter telephone
• Confirming proper system supervision

Installation should follow the applicable Simplex instructions and approved fire alarm drawings.

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Testing & Maintenance

Inspection should verify:

• Backbox is securely mounted
• Enclosure is not physically damaged
• Corrosion is not present
• Conduit connections are secure
• Internal wiring is protected
• Telephone assembly is securely installed
• Door operates correctly
• Telephone handset is accessible
• Remote telephone communicates correctly with the master station
• Firefighter telephone circuit supervision operates correctly

The backbox itself requires minimal maintenance beyond inspection for physical condition and secure mounting.

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Product Identification

• Manufacturer: Simplex
• Parent Company: Johnson Controls
• Model: 2975-9053
• Product Name: Firefighter Phone Backbox
• Product Type: Emergency Telephone Backbox
• Series: 2084 Series Firefighter Telephones
• Application: Remote Firefighter Telephone
• Color: Red
• Height: 13 in / 330 mm
• Width: approximately 9 9/16 in / 243 mm
• Depth: 3 1/2 in / 89 mm
• Pre-Installation: Supported
• Electrical Power Required: None
• Addressable: No
• Phone Assembly Included: No; ordered separately
• Related Backbox: 2975-9313C, without knockouts
• Associated Telephone Families: 4590-B / 4590-BX / 4590-C / 4590-CX

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Applications

Suitable for:

• Firefighter Telephone Systems
• Emergency Communication Systems
• Simplex 2084 Series Equipment
• Remote Emergency Telephone Stations
• Fire Command Center Communication Systems
• High-Rise Buildings
• Hospitals
• Hotels
• Schools and Universities
• Government Buildings
• Commercial Buildings
• Industrial Facilities
• Institutional Facilities

The Simplex 2975-9053 Firefighter Phone Backbox provides the red enclosure required for compatible Simplex remote firefighter telephone assemblies. Its 13 × approximately 9.6 × 3.5-inch construction and pre-installation capability make it suitable for permanent firefighter communication stations in commercial and institutional fire alarm systems.