GSM gate opener: open your gate from your phone, from anywhere

The unit is a stripped-down phone: a GSM modem and a SIM card, with relays that can do what a remote's button does. It sits beside the motor, wired to the motor's trigger input, and keeps a list of the phone numbers allowed to use it.

When one of those numbers calls, texts or taps the app, the unit checks the number against its list and, if it's allowed, closes its relay for a moment. The motor sees that as a press of a remote and opens the gate. Numbers that aren't on the list are ignored, which is the whole security of the system: adding a person is adding a number, and taking someone off is deleting one, with no remote to get back.

Most units can also report back. A gate that's been left open, a power failure at the motor or a low battery can be sent to chosen phones as a text, a missed call or an app notification, depending on the unit.

The G-ULTRA is Centurion's current GSM controller, and the one we fit for app control, notifications and complexes. Its full setup is on the Centurion G-ULTRA manual. The older MyGSM is still common on gates; it works without an app, which suits users with basic phones. The G-SPEAK ULTRA is for visitors rather than residents: it replaces a wired intercom handset with your mobile.

Generic modules sold under names such as RTU5024 and RTU5034 work on the same idea, but we have no maker's manual for them, so we don't publish their wiring or setup.

• Complexes and estates. Hundreds or thousands of residents can be given access by number instead of by remote, and a resident who moves out is removed in seconds. MyGSM holds up to 5,000 numbers, and G-ULTRA access lists can be imported from a spreadsheet and kept up to date the same way.
• Homes where remotes keep getting lost. Everyone already carries a phone.
• Letting someone in from a distance. A delivery, a cleaner or a family member at the gate can be let in while you're at work, or given their own number with set hours.
• Knowing what the gate is doing. A G-ULTRA can tell you the gate has been left open, or that the motor has lost mains power, before you get home.
• Older motors with no app. For a motor set up on its own display or dials, Centurion's route to phone control is a GSM module.

This is where the units differ most:

• G-ULTRA comes with a SIM contracted through Centurion to MTN, which only works in Centurion products. Running the apps on it costs nothing for the life of the unit, while SMS notifications and outgoing calls use Centurion's airtime, called tokens, bought in G-WEB. Another South African network's SIM can be fitted instead, but G-WEB then can't manage its airtime. The phones that use the gate can be on any network.
• MyGSM takes your own SIM. Centurion advises a prepaid SIM with little airtime on it, protected with a password, so it's worth nothing if stolen. Its PIN must be switched off, call forwarding must be off, and on a contract SIM caller ID has to be enabled too.
• G-SPEAK ULTRA takes a nano SIM, or in South Africa an e-SIM.

Caller ID matters. A MyGSM unit recognises users by their number, so anyone who calls with their number hidden won't open the gate. Missed calls and "Please Call Me" messages cost the user nothing.

Signal matters more than anything. Centurion calls network coverage best-effort, and a unit in a weak spot answers slowly or not at all. We check the signal at the gate before fitting, and fit an external antenna where it's needed.

On a Centurion sliding gate motor, the wiring Centurion shows is short:

• Power from the motor's 12 V auxiliary output, so the GSM unit runs off the motor's battery in a power cut.
• A relay set to pulse, wired across the motor's trigger input, so it works exactly like a remote.
• The motor's status output to one of the unit's inputs, so it knows whether the gate is open or closed.

Centurion is firm about a few things: never power the unit from mains AC, which destroys it; keep it away from the motor's position sensor and its remote receiver; and power everything down, battery included, before wiring. The unit then needs setting up: a G-ULTRA in G-WEB, and a MyGSM by text commands from its administrator number, on Centurion's MyGSM web portal or by USB.

We fit, wire and set up GSM units on the motors we work on, and load the access list for a complex.

Centurion's SMART motors are set up and run from its MyCentsys apps on a phone, over Bluetooth within reach of the motor, and the SMART+ models add Wi-Fi. For a household that mostly wants to open the gate from the driveway, that needs no SIM and no airtime.

A GSM unit earns its place when you need any of these:

• opening from anywhere with signal, not just near the gate
• a long list of users, such as a complex
• users without smartphones, who can open with a missed call
• notifications by text when the gate is left open or the power fails

The two also work together: Centurion's MyCentsys Remote app controls a G-ULTRA as well as a SMART motor. More is on the Centurion SMART app.

• One person can't open it: their number isn't on the list, it was typed differently, or their caller ID is hidden.
• Nobody can open it: the unit has no signal, no power, a SIM that has been locked by a PIN, or, for text-based actions, no airtime.
• It opens late, or the app button doesn't change: weak signal at the gate; an external antenna usually helps.
• The remotes work but the phones don't: the GSM unit, its SIM or its wiring, not the motor.
• Nothing opens the gate at all: it's the motor. See gate motor not working.

The G-ULTRA's own screens and faults are on the Centurion G-ULTRA manual.

Tell us the motor's make and model, how many people need access, and whether you want notifications. We check the signal at the gate, recommend the unit, fit and wire it, set up the access list and show you how to manage it. All our spare parts are genuine, and every repair carries our six-month guarantee on our repairs. Your exact price is set in a free quote before any work starts. No call-out fee when we do the work. If no work is done, a R650 call-out fee applies.

Remotes for the same gate are on gate remotes, and GSM intercoms alongside other systems on intercoms.