GSM intercom, PA, and SMS relay control for remote and unmanned sites

GSM 2-Way Voice Communication System with Relay Control

The G1002GMS is a GSM-based communication and control device for remote and unmanned sites. It supports three operating modes: an assistance call point (visitor presses a button to reach a control room), a remotely operated public address system, and an SMS-controlled relay to remotely restart or switch equipment. Two 5A relays are built in. Wall-mount form factor for feeder pillars, gate intercom points, and remote equipment enclosures.

Three Operating Modes

Assistance Call Point

A visitor or site occupant presses the call button. The device dials a pre-configured phone number. The operator on the other end can speak and listen — full two-way voice over GSM. Multiple dial-out numbers can be configured for escalation or round-robin calling.

Remote Public Address System

An authorised person calls the GSM number of the device from any phone. The device auto-answers and broadcasts the voice through an externally connected speaker (3.5mm audio jack). Useful for announcements at unmanned sites, guarded entrances, and remote facilities where a one-way PA needs to be triggered remotely.

SMS-Controlled Relay (Remote Equipment Restart)

Two built-in 5A relays can be triggered via SMS from authorised phone numbers. Used to remotely restart routers, modems, pumps, or any equipment that requires a hard power cycle. The device maintains a whitelist of authorised numbers — only registered phones can operate the relays.

Use Cases

• Unmanned substations and feeder pillars — call-for-assistance intercom
• Bank ATM kiosks — customer assistance call button to contact branch or call centre
• Gated communities and remote sites — visitor intercom at gate without running network cable
• Remote equipment rooms — SMS relay to restart network equipment or modems
• Industrial PA — remotely triggered announcements at factory floors or warehouses

Key Specifications

• Connectivity: GSM (2G)
• Voice: Full duplex two-way audio over GSM call
• Speaker output: 3.5mm audio jack for external speaker
• Relays: 2 × 5A relay outputs — SMS controlled
• Authorised numbers: Configurable whitelist for call and relay control
• Mounting: Wall mount
• Power: DC supply