Three-key hands-free analog waterproof and moisture-proof intercom phone for utility tunnel.

I. Function Overview
1. Wall-mounted installation, made of SMC material through forging and pressing, with a sprayed plastic surface. The color can be customized, and the appearance is aesthetically pleasing.
2. Supports connection to digital program-controlled exchanges or local telephone interfaces.
3. Supports three groups of hands-free one-touch direct calls, with status indicator lights.
4. Built-in 2W speaker, supports automatic answer on incoming calls, and detects busy tones to hang up.
5. Supports LED status indicator lights, with options for different statuses.
6. Powered by telephone line feed, no external power supply required.
7. Built-in digital noise cancellation circuit for active noise reduction to ensure call quality.
8. Supports call time limit settings.
9. Supports automatic answer after a set number of incoming call rings.

II. Operation and Usage
1. Power On/Off: Controlled via the hands-free button.
2. Answering Calls: When there is an incoming call, the phone rings. Press the hands-free button to talk or wait for automatic connection.
3. Making Calls: Press the corresponding hands-free button to dial the pre-set number. Lightly tap the button to end the call after conversation.

III. Main Technical Parameters
1. Supports connection to digital program-controlled exchanges with feed voltage of 48-60V or local telephone lines.
2. Temperature: -35°C to 75°C; Relative Humidity: 10% to 90%; Atmospheric Pressure: 86–106 kPa; Ambient Noise: ≤100 dB(A) 
3. Power Supply: Telephone line feed, no external power required.
4. Built-in Speaker: 8Ω2W, customizable to 5W.
5. Protection: Shell protection rating IP65, impact resistance rating IK10.
6. Call Distance: ≥90 cm

IV. Packaging Dimensions
Unit Dimensions: 308*188*134 mm
Packaging Material: Carton
Gross Weight: 5 kg
Net Weight: 7 kg